Turn the unit back to standalone mode. Load 2 song, one on deck 1 and 2.
Deck 2 is playing song and fader slider is all the way to the right. Go and press play on deck 1 with deck 1 cue button light off, song comes on headphone, ( it shouldn’t ), go and press deck 1 cue button and cue button light turn on, ( headphone music turns off, it shouldn’t , it should be the other way around).
The first time it happened to me was during a wedding gig. The unit just reset it self and went to cue issue.
BTW I have video of this bug happening, if the devs wish I could try to dig through the ~6 hours of footage to see what I did to trigger the bug when I have some free time.