diff --git a/src/Umbraco.Core/Persistence/Factories/PropertyGroupFactory.cs b/src/Umbraco.Core/Persistence/Factories/PropertyGroupFactory.cs
index 92ac5a55ba..0e35cb956d 100644
--- a/src/Umbraco.Core/Persistence/Factories/PropertyGroupFactory.cs
+++ b/src/Umbraco.Core/Persistence/Factories/PropertyGroupFactory.cs
@@ -108,7 +108,13 @@ namespace Umbraco.Core.Persistence.Factories
                                       };
 
             if (tabId != default(int))
+            {
                 propertyTypeDto.PropertyTypeGroupId = tabId;
+            }
+            else
+            {
+                propertyTypeDto.PropertyTypeGroupId = null;
+            }
 
             if (propertyType.HasIdentity)
                 propertyTypeDto.Id = propertyType.Id;
diff --git a/src/Umbraco.Core/Persistence/Repositories/ContentTypeBaseRepository.cs b/src/Umbraco.Core/Persistence/Repositories/ContentTypeBaseRepository.cs
index db3b846851..ca52678b91 100644
--- a/src/Umbraco.Core/Persistence/Repositories/ContentTypeBaseRepository.cs
+++ b/src/Umbraco.Core/Persistence/Repositories/ContentTypeBaseRepository.cs
@@ -255,9 +255,11 @@ namespace Umbraco.Core.Persistence.Repositories
                     propertyGroup.Id = groupPrimaryKey; //Set Id on new PropertyGroup
 
                 //Ensure that the PropertyGroup's Id is set on the PropertyTypes within a group
+                //unless the PropertyGroupId has already been changed.
                 foreach (var propertyType in propertyGroup.PropertyTypes)
                 {
-                    propertyType.PropertyGroupId = propertyGroup.Id;
+                    if(propertyType.IsPropertyDirty("PropertyGroupId") == false)
+                        propertyType.PropertyGroupId = propertyGroup.Id;
                 }
             }