I have a very similar problem to these threads: Eclipse Problems View not showing Errors anymore and Eclipse Problems View doesn't show Errors
However, my problem is that warnings are not showing up any longer, instead of errors. Errors show up just fine. They aren't showing up in files either. I tried the solutions in that thread anyways, but no luck.
I even tried going to Configure Contents and added a configuration to show everything with severity of "Warning". I tried moving the project to another computer, and warnings showed up just fine. I tried re-installing Eclipse, and the same issue appeared. Any other ideas?