I have been having this issue for a few years now and have found no way to truly fix it. Basically, if I have a VPN active in the owner profile, all secondary profiles can no longer access the internet at all unless I go back to the Owner profile and disable the VPN. This happens regardless if I have the 'Block connections without VPN' setting toggled or not for the specific VPN connection I am using in the Owner profile.
Is there any real way to fix this issue? Or is this a permanent Android bug that will not be fixed upstream?