only groups that I'm a member of are inherited when I fork, select 'Inherit repository user/group permissions'

Origin repo has 2 or more groups with privileges. I fork and select the 'Inherit repository user/group permissions' checkbox. My fork inherits the groups of which I'm a member, but none of the others.

I'm not sure if that's what you intended because I can't find any documentation on how this is supposed to behave, but as-is, it seems of limited use and is certainly not intuitive.

See BCLOUD-3808 for a related, but distinct bug related to groups.