In the last few days I have lost the ability to either snooze or dismiss a calendar reminder. It was also duplicating the reminders that were not acknowledged. Searching, this seems to be a recurring issue (since 2008 that I found). Generally the discussion revolves around Google calendar. I started using Thunderbird about 6 months ago (when Outlook 2013 was no longer supported by GMail). I initially imported my calendar, and have since then used TB as my primary calendar tool. I don't use Google calendar at all. My TB calendar is synced to iOS using TbSync I believe. Up until a few days ago the snooze & dismiss functions worked perfectly. I think (but not absolutely certain) that one of the many TB updates happened a few days ago as well. It is now on 102.4.1 (64-bit). Windows 11 did an update last night but this issue started a few days before that. Today I read in one of the threads to check the TbSync add-on, and it seemed to show and error. When I clicked on it, it took me to the latest TbSync and I installed that no problem. Closed TB and restarted. I also unticked the box for "Show missed reminders for writable calendars" (and restarted TB). I would assume that this may prevent the multitude of reminders showing up, but it did nothing to enable snooze & dismiss. I have just created a "Test" event in TB which synced across to my iPhone instantly, so the syncing works just fine. If anyone can shed some light on what has changed and how to restore snooze & dismiss, I would appreciate it.