CDJ 3000 Beatmatching Problem

Hey guys, I just got a pair of 3000’s and i’m experiencing them audibly drifting out of sync after being perfectly beatmached. no matter if i beat match by ear or sync, once i have them beat matched, they fall out of sync after 15-30 seconds. Tracks are same BPM. (Note: when sync is on on both players, this doesn't happen) - but I don't want to play on sync.

Once tracks are beat matched they should run together for the duration of the tracks, no? or is it normal that I have to adjust the jog wheels constantly? i had an xdj rx2 and didn’t have do adjust the jog wheel constantly once two tracks of the same bpm were matched.

Also just updated the firmware and the problem is still present. Any idea?

Edit: I just tried playing without the ethernet cable. Loaded the 2 tracks on two different USBs and they still drift out of sync after about 15-20 seconds - after being perfectly beatmatched.