For 4.27/5.0 (as part of [Link Removed]) we changed the asset manager's settings to be a key-indexed config array which gives more safety with removing entries via the UI. However, this actually broke many licensees because it causes the "!PrimaryAssetTypesToScan=ClearArray" line (which is used in our samples and documentation) to fail, leaving the array in a broken state. The ! syntax appears to only half work with key-indexed config arrays
The desired behavior is that line should delete all entries in the PrimaryAssetTypesToScan array. However, what happens in 5.0/4.27 is that it still loads the old values from BaseGame.ini, but doesn't show them in the project settings UI. So you end up with invisible engine-defined types that break any game-specific types that could conflict. You can work around this by using the in-game project settings UI to save the updated list, but it is broken for licensees until you do this.
The correct behavior is that the Map type should not exist at all and there should be no warning message. The engine's built in Map type is conflicting with the game's desired Level type
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-127694 in the post.