That doesn't seem to work reliably either. Clearing the derived data and then running seems to do the job though.

Thank you so much MobileTen! The problem in my project is that building the project does not update the strings file, only running the app does! The "Use Compiler to Extract Swift Strings" setting has a straight up misleading name. It does seem to work as intended for small project though. Weird.

This worked for like 5 minutes for me, now the error messages are gone again even with Live Issues disabled.

I'm also struggling to see diagnostics information. It doesn't show in the Xcode debug console (as you said, but the article still suggests it does), and it also doesn't show in the Console. Setting the filters results in nothing showing up.