Hi all,
First, best wishes to all in 2016 !!! (my first post this year)
Just ran into this issue this morning, while listening to my project from yesterday… One instrument channel (Padshop Pro) will not play anymore in the mix. Only when soloed, the channel will play. I also found out that Solo Defeat lets the channel play in the mix again, I just never use this function and I am not sure if this is intended behavior.
Any advise from you guys?
Thanks!
Seems to be an ongoing bug. Had this many times. Even duplicating track results in same behaviour. You will most likely need to create a new instrument track and copy your data over.
Hi Steve,
Thank you very much for your feedback.
I will check your solution later today. I suspect that having a separate midi track for mod wheel automation could be a cause as I did that for the first time on said channel last night.
Again thank you very much!
This workaround fixed the issue! Hope this does not happen often.
Again muchos gracias!
Yep, I’ve had this and I copied the data to a new track as the workaround. Seems infrequent and I’ve never been able to reproduce it, but there is definitely a bug there somewhere.
Mike.
Had the issue intermittently here as well…for me hitting the “Defeat All Mute States” button usually does the trick.
Thanks for this thread! I just hit this issue. Solved it by toggling “Deactivate All Mute States.”
I just got nailed with this for the first time, and I was scratching my head over it for about a half an hour thinking I did something wrong. 
Thank you for your solution!
Thanks! This solved the issue. Very weird bug, though.
It’s still present in 9. Point five. Sigh.
I have a theory that what’s really happening here is the track is actually just muted, but Cubase isn’t showing that it’s muted. If you run into this, try hitting mute on that track and then unmute the track.
I was able to fix the issue on a couple instrument tracks that I’d previously disabled. When I re-enabled them, they wouldn’t play unless soloed. Then I hit mute on the problem track, then unmute, and there was the sound. For me it worked on Kontakt and Omnisphere tracks where this had happened.
If that doesn’t clear up the issue for you, another solution I found from an older thread suggested adding a new MIDI track right below the problem track. This worked for me as well. Add the MIDI track and then the problem track works again. Then you can delete the new MIDI track.
Cool info. Thanks.
Great suggestions here - thanks 
“Deactivate all mute states” solved it for me in C10. Had this issue in 9.5 as well, really annoying. I will try the mute/unmute next time it happens to me.
I don’t know about others, but this only happens sometimes when I use retrospective record, which I use most of the time for midi.
Almost two years later, confirmed your theory. Simply hitting the Mute button on the track and unmuting worked. Thank you!
Thank you so much for pointing out the obvious fix! Can’t believe this is still an issue after a number of years.
Just had the same bug. I can’t believe Steinberg haven’t fixed this. I’m using 10.5
In version 12.0.70 the bug is still present. The bug is harmful, because in a project of 50 tracks you may not notice when one track is accidentally muted, and the final mix will be made incorrectly.
Well… even 5 years after the first OP on this, thanks to all for this.
I have Cubase 12 Pro and this has been drivin’ me nuts, and now I can not have to create a new track and migrate everything from the original over to it (since duplications don’t fix this, at least in the long run) .
Well it seems like we should keep the flame alive on this one
Yes - this is still present in 13.0.21
The bug that keeps on giving…