I have just installed Thunderbird 139.0.2 and I am no longer getting event reminders. How can I restore the capability to have the event reminders displayed?

Fixed this event reminder problem: checking the settings box to "Show missed reminders for writable calendars" enabled Thunderbird 139.0.2 to open the reminder box to show the event before it is going to happen, as well as showing the event after it was going to happen. Never had to explicitly do this with previous versions of Thunderbird in the 20+ years I have been using the Thunderbird calendar.