Every one of your roles is read at sign-in

If you held more than ten access grants, only ten of them were read when you signed in. The rest were dropped, so roles you genuinely had simply were not there — and screens those roles unlock answered "Access denied" instead. Nothing failed and nothing was logged, because a shortened list of grants looks exactly like a shorter list of grants.

All of your grants are now read, however many there are. The same applies to the lookup that finds your account in the first place, so a signed-in user is no longer at risk of being sent back to the sign-up form as though they had no account.