Cannot set event reminder in Thunderbird-Lightning

Cannot set event reminder in Thunderbird-Lightning

If I create an event in Thunderbird-Lightning, it is properly created in the Zoho Calendar except for the reminder.  If I create the event and choose a reminder 15 minutes before, when I go to check the event, it has no reminder set--both in Thunderbird-Lightning and in the Zoho Calendar web interface.

Is there any way to create reminders using Thunderbird?  I am using Thunderbird 52.5.2 (current release version) on Windows 7.