update store when items are received so observable works

src/Umbraco.Web.UI.Client/src/packages/users/user-groups/collection/repository/user-group-collection.repository.ts

@@ -29,6 +29,10 @@ export class UmbUserGroupCollectionRepository implements UmbCollectionRepository
 
 		const { data, error } = await this.#collectionSource.filterCollection(filter);
 
+		if (data) {
+			this.#detailStore?.appendItems(data.items);
+		}
+
 		return { data, error, asObservable: () => this.#detailStore!.all() };
 	}
 }