Delay in environment loading during gameplay - Please help urgently

what about a widget with a black image that fades and is removed after a few seconds of opening the level?

I experienced the same and that is my workaround (cover the screen while it finish loading as is just 1 or 2 secs)

here are another answers:

https://www.reddit.com/r/unrealengine/comments/e2ikgh/why_does_the_level_start_before_everything_is/