How To Import a Mac Calendar ICS File (Transferring Calendar entries to MS Outlook from Apple/Mac) - Bug Workaround
I have just solved at least my original issue NO HELP AT ALL from Microsoft.
I exported the Apple Calendar to Downloads as tried before, creating an ICS file. (export....)
I mailed it to myself and then opened it IN THE CLOUD NOT on the Mac Desktop Outlook and hey presto it loaded first time, so the key is to import by accessing:
https//outlook.com
Click on email with ICS attachment you mailed to yourself
Open the ICS attachment in same email
Click on Home.ics, Open
and it will then import.
I do wish Microsoft would test software prior to release or monitor user forums and respond.