Stereo out channel is going to zero a few bars into a track as if automated

The Stereo out channel is descending to zero a few bars into a particular track as if automated. I’ve tried resetting the channel and deactivating read automation on it but nothing works. I have five versions of the track saved and this happens on version 4 & 5 but not 3. I’m faced with either copying all the tracks that have changes on them from version 5 and pasting them into version 3 or creating a new version and copying into that track by track, as if I paste all tracks the same issue pops up. I’m using Cubase Artist 11 and Windows 10 on a Dell Latitude. Anyone out there have any idea what I’ve done and how I can fix it? Basically I’m a songwriter not a programmer so go easy on me!

I would create a new Stereo Out channel and re-route everything to that.
No idea what’s causing your issue but when I’ve had issues with the Stereo Out in the past (not recently FWIW) I’ve ended up creating a new one.

Thanks for that planarchist, I think I’ve tried that (I was getting pretty desperate the other night, trying to fix it long after I should have given up and gone to bed) . But I will try again. I’ve now created a new project and pasted everything into that. I thought this had fixed it but I went for some lunch, came back and there the slider was again at zero. I’d obviously imported the problem along with the tambourine, guitar and Spitfire Labs tracks! I’ve reset the stereo out again and will keep a close eye on things. I hesitate to open a support ticket as it takes so long but it is stressing me out a bit. Okay, a lot. Thanks again for your input.