IntelliJ just reloaded my project and removed all modules ? Now no class etc. gets recognized. How can I fix that?

I think syncing Gradle should fix it

No that didn't help

What error did you get? That is how you should do it.

also, try deleting the .idea, and the .gradle directories, then invalidate caches + restart IDEA

weirdly this only happens when I add that dependency: https://github.com/korlibs/korio

What's the error message? We can't help without it.

there is no error

If you run

gradle tasks

or similar, do the tasks for the modules that disappeared show up?

Looks like korio doesn't have one of the targets you are targeting thene

I was facing similar issues in the past too and what helps additionally to hints from @andylamax was running gradle build in terminal from CLI with

--info

or even

--debug

Sometimes are error messages displayed in CLI run not showing in or hard to find in IntelliJ&Co