So I have this problem, it started few days ago. I have no idea why.
When I'm editing code, I get some inspection warnings and after I'm done editing the warnings won't go away. Even when I have correct code, I make small change (like removing parentheses or backet) to get the errors. Then i fix it, and inspection keeps all the errors active, dispite code beiing valid and correct. After restarting IDE, code is 'reinspected' and errors are gone, until i make some changes again.
I have attached three screenshots illustrating this.