Time sync off by 7 seconds

Yes, something is going on, but I don't know exactly what.  This morning, as is my habit, I casually compared the displayed time on my 6X Pro with my time reference and saw the same thing you did - time was off by approximately 6-7 seconds.  I sync'd using phone and the difference persisted.  I then sync'd using GPS and still had the same difference.  I was a little disappointed, but no big deal - yet.

Then, again as is my habit, I went to review the Garmin forums and found your post.  It was then time to do a little investigation on my own.

My time reference is a LeoNTP Stratum 1 Master Clock / Time server with GPS synchronised clock source which yields nanosecond level accuracy - specs can be found here: LeoNTP Master Clock Quick Specs

For the sake of this comparison, I simply took a picture of the 6X Pro next to the LeoNTP to see if they are within a second or so.  For a more exact determination of time offset, I would need to take a 120 frames/sec video and compare frame-by-frame.

With my 6X Pro still displaying about 6-7 seconds off, I thought it would be a good idea to sync with Garmin Express to make sure I had the latest software.  After doing that, displayed time was about one second slow:

I then performed a Sync using phone and it was still about one second slow:

Finally, I went outside and performed a sync using GPS and the 6X Pro still displayed time about one second slow:

I'm still not happy about the fact that neither a phone sync nor a GPS sync brought the time back in line as a first step this morning.  I will continue to monitor this, but at the same time, it would probably be wise for Garmin to take a look at this.

In the meantime, if you are still observing a 6-7 second time offset, try a sync with Garmin Express to see if that helps.

HTH