Owners in a Microsoft 365 group cannot edit the calendar
We have an Office 365 Small business tenant. There is a group that has been created, well call it "Accounting". It has 7 members. One of them, who is also an owner, told me if they try and move a meeting on the calendar they get a permissions error. They cannot create one either, it is essentially read only.
Working on this I have become more and more confused about things in general. So this group was created a long time ago. It has a SharePoint site and and email address. The user in question added the calendar as a shared calendar. As I said, he is an "owner" in the group. When this group was created, was the calendar also created? Are there different permissions that can be assigned to the calendar like other shared calendars (Reviewer, editor, etc.)? If so, where would I find those? Is this something I can only do via Powershell, or is it available in the GUI?
I guess my logic that if he is an "owner" of the group he should be able to anything with the Calendar is flawed.