gsimplecal works fine here.
If something does not work, always a good idea is to run it from terminal to see if there is some error. And paste this error in the forum post.
The terminal doesn’t give any message, it returns the prompt, but the process remains active. (ps -A |grep gsimplecal). I completely uninstalled it and reinstalled it… the same thing happened.
Yes, the line exist.
I tried many tests recommended by chatgpt and there was no case, he recommended installing snixembed, lxqt-policykit or libappindicator, would that help?