Playing a set this afternoon I experienced a condition that left me unable to keep songs in sync. Initially I thought there was a problem with the beat grid, so I deleted and recreated the grid. That didn't solve the problem.
Then I noticed the Traktor MIDI indicator at the top of the screen was flashing, almost constantly. So I loaded a MIDI monitor application to try and determine where the MIDI traffic was coming from, but there was no traffic to be found.
So I slid the platform that holds my computer towards me (I'm using an NI flight case) so I could check the cables and see if anything had come loose. And then the MIDI indicator stopped flashing. Apparently I jostled the mixer just right while I was sliding the platform. That solved the problem.
I continued investigating, and within a few minutes I found the root cause. Maybe this is a known issue, but it is new to me. It turns out that if I nudge a jog wheel in a particular way, I can cause the MIDI indicator to flash non-stop. And it seems this also impacts playback of the track.
I was able to reproduce this with both jog wheels.
FWIW, I tried to reproduce the problem with my S2MK3, and I was unable. Perhaps the problem only exists on S4MK3.
Anyways... I just wanted to share this experience in case someone else has a similar experience. Hopefully I can spare someone some frustration.