Hello,
Sorry but I think you misunderstood our question (sorry english is not my main language) ... and at the same time we made some progress understanding our problem.
At first the problem was: we can only see extended user profiles that are admins, we do not see the profile of somebody who is just a contributor. If we give admin role to that user, we can see the profile, if we bring back that user to let's say "editor", we cannot see his profile anymore.
After making a lot of tests and reading a lot of threads here, we finally understood that the key was not the role of the user, it was the fact that this user already had posted something or not ... the coincidence being that we had only published posts with admin accounts ...
We found in the forum that you can add the following filter in WP to force displaying profiles of people with no posts:
add_filter('wpforo_profile_field_displaying_restriction', '__return_false');
However, even after adding this in our child theme functions.php we are still unable to view all peoples profiles (I mean we see the people, but when clicking on one of them, the profile is empty and does not show any of the extra fields we created ...). Of course, created fields have been given the proper settings to be displayed ...
So yes, if you have some ideas, they are welcomed !
Oh and BTW, that option you mentionned is ok.
Pierre.