I was trying different combinations of group security options today when I realized none of the users I had created are able to change the assignee on a bug EXCEPT for admin accounts. This what's happening now:
With a non-admin user, when I'm uploading a bug, the assignee and CC fields show no options at all. After the bug was filed, it is assigned to the default user and it shows correctly on the interface. When I try to assign the bug to someone else, the assignee field shows only the default assignee, so the same as before.
Admin users can select and change assignees at any time. I've cleared all the changes made regarding security but it didn´t help. Now, I'm not sure if this is normal behaviour or I'm looking at a defect.
I did some research before posting but I was unable to find anything :-/ so ANY tip will help.