After an evening and overnight on 2m JT65B I have now returned to 10m JT65A. I also checked the PC was synced to internet time. It was.
UPDATE 1245z: As yet, no spots given or received on 10m JT65. Disappointing.
UPDATE 1658z: Only UK spots of others so far today on 10m JT65. If I am honest, this has been surprising and disappointing as I was expecting greater things on 10m JT65 today. Best spot was G4CJC (73km).