Hi Radu,
The problem was still there, you have succeeded to register just because the checkbox fields were not anymore mandatory – I changed this to test what Laura suggested initially. In this case, if selected something in those fields no value was actually saved.
Anyway, few minutes ago I got a notification that there is a new BuddyPress update version and looking into the list of bugs they have solved I found the following:
#7845 closed defect (bug) (fixed)
User registration fails if multi-option multi-select or checkbox involved
It was exactly the issue I had. I have upgraded BuddyPress and registration is working fine again.
Anyway, thanks for your support.
