We have a dozen or so room resource calendars in O365. There is one calendar we can't edit in Outlook. We can edit the calendar in OWA.
In (so far) every calendar I open, I can edit existing items or add/delete items. For the one I'm having trouble with Outlook throws the "You don't have permissions to this calendar, etc., etc." and if I double-click an existing item it prompts me to send an access request to the owner.
The only difference I can see is there is a "Resources" user that has Publishing Editor access rights on each of the calendars except the one in question.
If I try to add this "user" I get an error saying the user doesn't exist.I can't delete the mailbox and start over, it has a lot of items already in it. (You add appointments and meetings in your own calendar and the resource calendar is set to accept all.)
And Google...