My PC time is good, as I use Dimension4 to keep it good, and this is updated every minute. Maybe that is too often? Maybe the sync is confusing things?

73 de Phil GU0SUP

Phil, from what I've heard, Dimension4 is not very good time sync application.

And once a minute could well be way too often too.

Have a look at this email by late Bill Somerville, G4WJS: https://wsjtx.groups.io/g/main/message/28195

Perhaps switching to Meinberg or similar for time keeping could help?

I don't use Windows myself so I can not recommend any particular time sync application.

73's de Kari, oh2gqc