I just ran into this too .... just teamworked our first AC10 file, am signed in with exclusive access and cannot change ANY subset settings.
I can however delete those subsets although I cannot edit their settings ...
If I create a new subset (drag-copy) I can edit the new subsets settings ONCE. If I go back to edit them again its all locked ....
So for the moment I have a workaround .. if i want to change a subsets settings I duplicate the existing one, change its settings and delete the old one. The new one is locked so if i want to change anything else I do it all over again.
Seriously what the hell is going on here. I ran into this problem within 5 minutes of teamworking and it's making me slightly worried about what other little surprises AC10 Teamwork has in store for me (with deadline due in 1 week).
cheers,
Owen Sharp
Design Technology Manager
fjmt | francis-jones morehen thorp
iMac 27" i7 2.93Ghz | 32GB RAM | OS 10.10 | Since AC5