Thunderbird 52.9.1 (64 bit) Ubuntu 16.04 Lightning 5.4 Sometime in the last week or two, reminders stopped working for tasks. I rely heavily on this working - I set myself reminders of things to do or check on and if the reminder does not show up, things don't get done! One task that is acting this way is in my "Home" calendar - a native Lightning calendar, not a network provider. It is scheduled for today at 3:05 PM. I open the task and it shows "No Reminder". I set a reminder (I've tried 0 minutes before and 5 minutes before) and save the task. When I re-open the task it still shows "No Reminder". The log is not showing any errors.