Calendar reminders have stopped showing in reminder dialog

A week or so ago my Thunderbird (140.1.0esr) reminder dialog stopped showing up. No idea why. Calendars > properties does have "Show Reminders" checked. Account > Thunderbird Settings > Calendar > Show the reminder dialog (X) is checked. I've restarted and rebooted (Linux). I can add events to the calendar and they show up on my phone. I did update to 140.1.0 10 days ago, so perhaps this is a problem with this version. I'm considering reverting to the previous 128.9.1esr version, but it would be great if someone had a solution for this. THX