Async Loading Screen is a free and open-source plugin for Unreal Engine. Async Loading Screen allows you to easily configure a Loading Screen System in the project settings, and automatically add a Loading Screen whenever you open a new level, without Level Streaming.
Just update the plugin to UE 5.1.0. Please update your project to UE 5.1 if possible
I made a question on the official UE fora, as this was clearly a bug in the engine. With the latest release, this should be fixed: https://forums.unrealengine.com/t/game-movie-player-black-screen-when-loading-is-finished/662145/5
@TovenaarAndreas Thank you for creating this thread. I've checked the plugin in UE 5.1 and confirm that the issue is fixed now.