https://github.com/EpicGames/UnrealEngine/commit/638d9319d0a5c96ee829f0a62bd28c24ca41e159
This fix may be the reason why the loading screen becomes black if you set “Minimum Loading Screen Display Time > 0”, it doesn’t exist in ue4. Since it is related to engine code, nothing I can do about it right now. You should set Minimum Loading Screen Display Time to -1 atm. I’ll look for another solution in the future.