Errors not visible in Text Editor In VS2022 Community

I have already explained and tried to solve my issue on StackOverflow in the following post:

https://stackoverflow.com/questions/78642589/errors-not-visible-in-text-editor-in-visual-studio/78645955?noredirect=1#comment138693989_78645955

In short, I had ReSharper installed as an extension in VS2022 Community, but regulary had an error that ReSharper had stopped working and VS proposed to disable the extension. I did this and since then have the issue that I can't see errors in my Text Editor for C#-code. They appear in the Error List, but no squiggles are visible in the Editor and no red dot in the scroll bar. Double clicking on the errors in the Error List also stopped working. Errors is Xaml do still appear as squiggles.

I tried various approaches. I uninstalled VS with InstallCleanup.exe, as well as manually removing all leftover data. I uninstalled, reinstalled, repaired, disabled, uninstalled again,… ReSharper. I also deleted all ReSharper (and JetBrains) files I could find, but all without succes. I don't know where certain files of settings may still be hidden, but maybe I missed something.

I strongly suspect ReSharper to the culprit, but I'm not entirely sure. I someone has another suggestions, I would appreciate it a lot.

Extra note: double clicking on something in the Task List window also doesn't automatically jump to the task. Maybe this is also related. However ‘Find All’-results or the ‘Reference’-window for example don't show this issue.