Occasional click with 10.5

I am experiencing an occasional click - like the one that happens when sync is lost - since upgrading to 10.5.

I am running windows 10 with a RME Rayday card. Everything is nicely synced - clock master is my SSL converter.

Any ideas what this could be? Anybody else experience issues? Never had this when I was still on 8.

Regards,
Dirk