Description
Texture Group should be set to UI and Compression Settings to UserInterface2D
Don't package the Movies folder into the .Pak file because MoviePlayer needs to look for the startup movies folder at "Contents/Movies" path
Make sure you don’t have any plugins enabled that conflict with ASL. For example, Pre-Load Screen Movie Player
Background images and Loading icons may not appear in packaged games or Quick Launch unless their asset folder is added to AdditionalAssetDirectoriesToCook. This is because the plugin loads at the PreLoadingScreen phase — before the asset streaming system is ready — so textures must be explicitly cooked. In Project Settings → Packaging → Additional Asset Directories to Cook, add the folder(s) containing your loading screen background images (e.g., /Game/LoadingScreen/Backgrounds). This applies to Image Sequence images as well.
Are you looking for a loading system without Level Streaming? If yes, then you already found GOLD :)
Usually, you have to use Level Streaming for loading screens because the User Widget is destroyed at level transition, and level loading runs on the main thread, which blocks any other game activities until it's completed. So, you will need to manually control which object is loaded/unloaded. Also, you can't use different Game Mode and Player Controller for each level, and sometimes there's still occasional freezing.
That said, you may need to change your game logic to fit with the Level Streaming mechanic, and it requires a lot of work to achieve a simple thing: Add a Loading Screen. To create a custom loading screen without Level Streaming, you must do it in Unreal C++. However, this is a challenging task for artists and designers, even for developers unfamiliar with the Slate framework and engine module code. Async Loading Screen plug-in comes to the savior.
Async Loading Screen allows you to configure a Loading Screen System in the project settings easily and automatically adds a Loading Screen whenever you open a new level. It also comes with pre-designed UI layouts and default icons, making it easy to customize your loading screen in a few minutes.