Post "event reminder not working " reads as Solved. That post has a lot of discussion about the task reminder pop-up not working. I've tried all of the relevant remedies with no success, so I posting this more specific topic. My tasks are not appearing in the reminder popup window with the calendar events. None of my previously created tasks are popping up. They do appear in the Task window, but not in the pop-up window. Sometimes, if I create a NEW reminder for the same day when Thunderbird is on or for a future day for a time when Thunderbird is on, the task pops up, other times it does not. If I change the date and time of a previously created Task to the current date and a future time when Thunderbird is on, it still doesn't appear in the pop-up window and sometimes it disappears from the Task area of the main Thunderbird window, but still appears if I open the main Task window/tab. If I get a NEWLY created Task to appear and I snooze it for a time when Thunderbird is on, sometime it pops-up again and other times it does not. I do not use Google calendar or any other calendar, just Thunderbird (Lightning). Thunderbird 142.0 (64-bit) Edition: Windows 11 Pro Version: 24H2 OS build: 26100.4946 Experience: Windows Feature Experience Pack 1000.26100.197.0