I am able to accept invitations from new appointments ("This message contains an appointment invitation", with the regular action buttons). But if it comes to appointment update messages, I have no action buttons. Only the message "Diese Nachricht enthält eine Termineinladung". Please see the screenshots. I've already tried with troubleshooting mode (without addons etc. https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird#w_starting-thunderbird-in-troubleshoot-mode), this makes no difference, the issue persists. TB Version is: 115.1.0 (68-Bit on Windows 11)