Bathroom caulking and repairs in Pickering nearly always come back to airflow. The Amberlea and Liverpool houses from the seventies and eighties were built with a small builder grade fan, and a lot of them are still running, pulling almost nothing while the shower fills the room with steam.
Sealant does not stand a chance in a bathroom that stays damp. So I cut out the mouldy bead and reseal it properly, then look at the fan and the duct behind it. Regrouting, loose tile and vanity joints get sorted in the same visit.