The logic in the AssetManager to determine if a scanned Blueprint should be added to the primary asset directory is wrong if that blueprint has an active redirect targeting it. The simplest way to repro is to set up a package redirect for one of the template projects, which happens for any project made using a template.
The proper fix is make sure the redirect logic is handled properly in the blueprint scanning code
1. Compile EngineTest
2. Change
+PackageRedirects=(OldName="TP_FirstPerson",NewName="/Script/EngineTest")
to
+PackageRedirects=(OldName="/Script/TP_FirstPerson",NewName="/Script/EngineTest")
in DefaultEngine.ini for EngineTest
3. Load the editor, then create a new Actor blueprint in /Game/Tests/Gameplay/AssetManager/ExampleBlueprints
4. Shut down and reload the editor
5. Open Asset Audit window (window->developer tools), Hit Add Primary Asset Type and select EngineTestPrimaryAssetBlueprint
6. Your actor blueprint should not be added to the window. If it is this bug exists
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-50571 in the post.