Sky box corrupted/ missing when switching to compatibility mode

I want to post my game to itch, but when I switched to compatibility mode I couldn’t open my main “universe” scene and get the following error:

Failed loading resource: res://Backgrounds/SkyBox.exr. Make sure resources have been imported by opening the project in the editor at least once.

and then this error afterwards:

Failed loading resource: res://universe.tscn. Make sure resources have been imported by opening the project in the editor at least once.

If I try to open the universe scene I get this pop up:

If I click open anyway it says it’s corrupted. It seems like the skybox is stil in the right place:

It keeps loading and reimporting the skybox file- what should I do?

Thanks!