I’m really stuck and have no idea how I got there 
I have inputs in AB, CD. Track #1 is a thru track and plays AB just fine. Track #5 is a thru track but only plays CD when I cue track #5. From what I can see, settings on both of the tracks are the same other than the inputs.
I have nothing connected to the cue outputs.
Any ideas of what buttons I’ve accidentally managed to press to get me into this state?
I’m not in front of anything at the moment, but I do know there are different cue behavior settings you can choose. Perhaps you changed this at some point?
I don’t believe I’ve adjusted the cue behaviours in settings, but even if I have, why would 1 track behave differently to the other. Track #5 just doesn’t play at all unless I cue it; track #1 plays exactly as I would expect.
Can you reload to a previous save state? Does this happen with a new project?
Check the mixer menu for muted or solo’ed tracks.
Well, good news is I’ve learned about solo’ing tracks from the mix page. But that wasn’t it, sadly 
With a new project it seems to work all ok, but I had to unplug my midi keyboard from the octatrack and plug directly into the synth to get anything working …
… it wouldn’t be anything to do with midi that’s causing this, would it?
(At least I know I could start again with a new project, so next time will be good, but there’s a lot of effects on neighbour tracks I’d have to re-do which would be a pain, but not impossible)
Select an empty scene, could be the culprit.
Well, beside the usual suspects (CC messages) the OT may react to incoming MIDI notes with a broad varity of actions depending on the active note mapping (like start recording, send the active track to cue etc. pp.). See the manual for all the details.
BTW: Are you sure you have added a play trig on track 5? Maybe cue’ing the track opens the AMP without a play trig …
So there’s definitely a trig on step 1 for track 5 (not 100% sure if it’s a play trig, sorry, still learning).
Crazily enough track 3, a static machine, is having the same issues…plays ok when cue’d but silent otherwise (whether muted or unmuted)
Of course I realise that the reason why i get output on cue’d tracks is because I’m listening on headphones, but I still can’t work out why my other tracks are silent when playing.
Creating a new project is fine, so it’s definitely a silly key press combo that I did whilst “learning”. Just would really like to work out what those keypresses were
Can mean LEVEL is at 0 (if the track is not muted).
I’d also check scenes settings, they can control LEVEL (XLV). You can check scenes quickly muting them with Function + Scene A/B buttons.
Just found a small note in the manual:
If Neighbor machines are used, muting the track or tracks preceding the last Neighbor machine will not have any effect. To mute the chain, mute the last Neighbor machine.
That was it. I had the neighbour track 6 muted which mutes the chain, but track 5’s led was still lit up. It still allowed track 5 to be cue’d. Unmuting track 6 allowed track 5 to be played normally.
Ho hum. I love this instrument, but sometimes it’s so frustrating to learn!
As well as it is frustrating to diagnose if you only provide half of the facts. This topic could have been resolved days ago if you stated the fact about using neighbour machines … 