NeoForge seems to be unable to access common code.

Hey there, hope you're having a nice day! I'm trying to port a fabric mod I've been maintaining to be multi-version and multi-platform. However, even without any custom code, NeoForge seems not to find the common code. Throwing a ClassNotDefException.
If this is just me, I'm sorry and I may be stupid if this is the case, but I just can't seem to figure it out.