The reminder will not appear because the item is in a folder that doesn’t support reminders. .....

I changed to the OST file as a default.  I can create an appointment in the calendar in front of me, but I still get the same error “The reminder for “xxxx” will not appear because the item is in a folder that doesn’t support reminders.  Is this ok?”  It also does not sync with my iPhone.

Outlook also added yet another calendar option under “My Calendars” called “Calendar (This computer only) – email@comcast.net.” 

I closed Outlook.  I then signed out of iCloud and back in.  All items seem to have copied back into Outlook.  I opened Outlook and I have selected Calendar – iCloud.  I can still create an appointment here but it still doesn’t sync with my phone and I get the same reminder error message.  Again, my default data file is file name@comcast.net.ost and not mailto:name@icloud.com.ost, in case i misunderstood you.

What did I do wrong?