Level Maps Compile every time I open them

Hi guys!
After I coverted my project to 4.16.3 to 4.20.3, the main level map starts compiling everytime (it only compiles 150 shaders out of 40,000 ).
I tried to delete the Derived Data Cache, as well as intermediate and saved folders, but the problem persists.

I’ve also tried another version of the engine (4.19) and the problem is still there.

Even deleting every assets within the map doesn’t seem to work. It still needs to compile those 150 shaders.

Do you know what could be the problem?

Thank you!

Actually every map of the editor has the same issue. So there must be something wrong with the project itself.