If it works correctly in other arenas, it must be a behavior implemented when they introduced custom arenas and gave players CM privs in their own arena - must have spilled into offline too. I guess your only option is to view the links in my earlier post and set up your controls for CM Eye movement in a seldom-used mode (I use mode 4, and switch to that mode with the * key).
So when I want to cruise around in God Mode, I hit F5 to enter God Mode, then * to activate mode 4 to control God Mode, and off I go.