Can’t change permissions for a Google Calendar that’s under “My Calendars”

We have a G suite account where all users add to and edit one calendar. When we got a new employee, as a Super Admin, I was unable to add them to the calendar nor edit the permissions.

I went on a hunt to figure out who it belonged to as I seemingly didn’t have access to it, telling me that it may be outside of our domain. Miraculously, after reactivating and logging into an old suspended account from a previous employee, I found it under “My Calendars”. When I tried to go edit the permissions, I ran into the same problem, the options had no dropdown/were greyed out and they only allowed people to view events.

So I exported the calendars and transferred ownership of the calendars to my admin account, but when I logged in, the transferred calendars displayed nothing. Luckily the export worked and I was able to bring in the calendar to a newly created calendar on the Admin account, but then that only allowed me to set it to view only again for the organization, everything else was greyed out!

I was able to add each individual account with the permission to edit, so in the end it worked out, but my question is why was I not able to edit permissions as a super admin or when it was listed under my calendar in the owners account, and why did nothing transfer over?