When a new user registers using LinkedIn (using CB Connect), some other profile fields set as required at registration (and including default values for those other required fields) seem to be bypassed. By "bypassed" I mean the new account is created without requiring values to be set for other required profile fields (including not applying default values).
Correct, that's how it's supposed to work. It's single sign on.
Is there a way to force new users who register using LinkedIn to complete other required profile fields before their account is created, similar to if they were registering directly through CB?
No, but you can set their first time login redirect to send them to profile edit for them to complete their profile, but it's not going to force them to complete it.