Calendar not allowing/displaying my default calendar

Zoho calendar is set as my default calendar. All my various Gmail accounts appear but Zoho calendar isn't listed. I've cleared defaults and when I go back into calendar when I try to add an event my choice of app is either Outlook or, you'll love this, VA (Veterans Administration app that I guess has a calendar). I'm in a loop.

To complicate the issue sometimes after forcing restart of Niagara launcher and restarting the phone my default Zoho calendar events show up. But when events revert back to default, which is not linked to any calendar, I can't figure out how to reselect Zoho calendar and my only choices are Outlook or VA.