RE: Assignee has insufficient privileges
It's been resolved.
Microsoft support identified the problem being that in CRM, his Client Access License (CAL) Information was set to Administrator, and not Read-Write.
For anyone to have the ability to create or own records in CRM, they have to be read-write. Even if they are a global administrator.
When we tried to save it, it said he didn't have a CRM license, which was odd, since he did have an active account.
Since we're a partner of Microsoft, we have a checkbox on each user at the 365 side to identify it they're using one of our CRM licenses. It was checked as it's supposed to.
So we unchecked it, let it sit for a while, and checked it again. This prompted the systems to sync up again, as I can best understand it as a non-technical person.
When I tried today, his CAL info was set to Read-Write, and I was able to save records to his name.
Thanks for all the help!