diff --git a/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeCommonRepository.cs b/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeCommonRepository.cs
index 194a00b7f2..645ab9f924 100644
--- a/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeCommonRepository.cs
+++ b/src/Umbraco.Core/Persistence/Repositories/Implement/ContentTypeCommonRepository.cs
@@ -240,6 +240,25 @@ namespace Umbraco.Core.Persistence.Repositories.Implement
                     propertyIx++;
                 }
                 contentType.NoGroupPropertyTypes = noGroupPropertyTypes;
+
+                // ensure builtin properties
+                if (contentType is MemberType memberType)
+                {
+                    // ensure that the group exists (ok if it already exists)
+                    memberType.AddPropertyGroup(Constants.Conventions.Member.StandardPropertiesGroupName);
+
+                    // ensure that property types exist (ok if they already exist)
+                    foreach (var (alias, propertyType) in builtinProperties)
+                    {
+                        var added = memberType.AddPropertyType(propertyType, Constants.Conventions.Member.StandardPropertiesGroupName);
+
+                        if (added)
+                        {
+                            var access = new MemberTypePropertyProfileAccess(false, false, false);
+                            memberType.MemberTypePropertyTypes[alias] = access;
+                        }
+                    }
+                }
             }
         }
 
@@ -264,7 +283,7 @@ namespace Umbraco.Core.Persistence.Repositories.Implement
             if (contentType is MemberType memberType)
             {
                 var access = new MemberTypePropertyProfileAccess(dto.ViewOnProfile, dto.CanEdit, dto.IsSensitive);
-                memberType.MemberTypePropertyTypes.Add(dto.Alias, access);
+                memberType.MemberTypePropertyTypes[dto.Alias] = access;
             }
 
             return new PropertyType(dto.DataTypeDto.EditorAlias, storageType, readonlyStorageType, dto.Alias)
diff --git a/src/Umbraco.Tests/Persistence/Repositories/MemberTypeRepositoryTest.cs b/src/Umbraco.Tests/Persistence/Repositories/MemberTypeRepositoryTest.cs
index 81d3b219ce..79e8e43804 100644
--- a/src/Umbraco.Tests/Persistence/Repositories/MemberTypeRepositoryTest.cs
+++ b/src/Umbraco.Tests/Persistence/Repositories/MemberTypeRepositoryTest.cs
@@ -171,7 +171,6 @@ namespace Umbraco.Tests.Persistence.Repositories
             }
         }
 
-
         //NOTE: This tests for left join logic (rev 7b14e8eacc65f82d4f184ef46c23340c09569052)
         [Test]
         public void Can_Get_All_Members_When_No_Properties_Assigned()
@@ -200,7 +199,6 @@ namespace Umbraco.Tests.Persistence.Repositories
             }
         }
 
-
         [Test]
         public void Can_Get_Member_Type_By_Id()
         {
@@ -233,51 +231,114 @@ namespace Umbraco.Tests.Persistence.Repositories
             }
         }
 
-        /// <summary>
-        /// This demonstates an issue found: https://github.com/umbraco/Umbraco-CMS/issues/4963#issuecomment-483516698
-        /// </summary>
+        // See: https://github.com/umbraco/Umbraco-CMS/issues/4963#issuecomment-483516698
         [Test]
-        [Ignore("Still testing")]
         public void Bug_Changing_Built_In_Member_Type_Property_Type_Aliases_Results_In_Exception()
         {
-            //TODO: Fix this bug and then change this test
+            var stubs = Constants.Conventions.Member.GetStandardPropertyTypeStubs();
 
             var provider = TestObjects.GetScopeProvider(Logger);
-            using (var scope = provider.CreateScope())
+            using (provider.CreateScope())
             {
                 var repository = CreateRepository(provider);
 
-                IMemberType memberType = MockedContentTypes.CreateSimpleMemberType();
+                IMemberType memberType = MockedContentTypes.CreateSimpleMemberType("mtype");
+
+                // created without the stub properties
+                Assert.AreEqual(1, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3, memberType.PropertyTypes.Count());
+
+                // saving *new* member type adds the stub properties
                 repository.Save(memberType);
 
-                foreach (var stub in Constants.Conventions.Member.GetStandardPropertyTypeStubs())
+                // saving has added (and saved) the stub properties
+                Assert.AreEqual(2, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3 + stubs.Count, memberType.PropertyTypes.Count());
+
+                foreach (var stub in stubs)
                 {
                     var prop = memberType.PropertyTypes.First(x => x.Alias == stub.Key);
                     prop.Alias = prop.Alias + "__0000";
                 }
 
+                // saving *existing* member type does *not* ensure stub properties
                 repository.Save(memberType);
 
-                //Assert.Throws<ArgumentException>(() => );
+                // therefore, nothing has changed
+                Assert.AreEqual(2, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3 + stubs.Count, memberType.PropertyTypes.Count());
+
+                // fetching ensures that the stub properties are there
+                memberType = repository.Get("mtype");
+                Assert.IsNotNull(memberType);
+
+                Assert.AreEqual(2, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3 + stubs.Count * 2, memberType.PropertyTypes.Count());
             }
         }
 
         [Test]
         public void Built_In_Member_Type_Properties_Are_Automatically_Added_When_Creating()
         {
+            var stubs = Constants.Conventions.Member.GetStandardPropertyTypeStubs();
+
             var provider = TestObjects.GetScopeProvider(Logger);
-            using (var scope = provider.CreateScope())
+            using (provider.CreateScope())
             {
                 var repository = CreateRepository(provider);
 
                 IMemberType memberType = MockedContentTypes.CreateSimpleMemberType();
+
+                // created without the stub properties
+                Assert.AreEqual(1, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3, memberType.PropertyTypes.Count());
+
+                // saving *new* member type adds the stub properties
                 repository.Save(memberType);
 
+                // saving has added (and saved) the stub properties
+                Assert.AreEqual(2, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3 + stubs.Count, memberType.PropertyTypes.Count());
 
+                // getting with stub properties
                 memberType = repository.Get(memberType.Id);
 
-                Assert.That(memberType.PropertyTypes.Count(), Is.EqualTo(3 + Constants.Conventions.Member.GetStandardPropertyTypeStubs().Count));
-                Assert.That(memberType.PropertyGroups.Count(), Is.EqualTo(2));
+                Assert.AreEqual(2, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3 + stubs.Count, memberType.PropertyTypes.Count());
+            }
+        }
+
+        [Test]
+        public void Built_In_Member_Type_Properties_Missing_Are_Automatically_Added_When_Creating()
+        {
+            var stubs = Constants.Conventions.Member.GetStandardPropertyTypeStubs();
+
+            var provider = TestObjects.GetScopeProvider(Logger);
+            using (provider.CreateScope())
+            {
+                var repository = CreateRepository(provider);
+
+                IMemberType memberType = MockedContentTypes.CreateSimpleMemberType();
+
+                // created without the stub properties
+                Assert.AreEqual(1, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3, memberType.PropertyTypes.Count());
+
+                // add one stub property, others are still missing
+                memberType.AddPropertyType(stubs.First().Value, Constants.Conventions.Member.StandardPropertiesGroupName);
+
+                // saving *new* member type adds the (missing) stub properties
+                repository.Save(memberType);
+
+                // saving has added (and saved) the (missing) stub properties
+                Assert.AreEqual(2, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3 + stubs.Count, memberType.PropertyTypes.Count());
+
+                // getting with stub properties
+                memberType = repository.Get(memberType.Id);
+
+                Assert.AreEqual(2, memberType.PropertyGroups.Count);
+                Assert.AreEqual(3 + stubs.Count, memberType.PropertyTypes.Count());
             }
         }