Presumably there is a limit on the number of particles that can be generated by each smoke-producing entity, and the smoke effects of many locos are improperly set up to produce particles at a higher rate than the limit permits over time. Once the cap is reached, any further particles are culled until those already being rendered complete their animation and disappear.

Not every locomotive suffers from this, so it should be possible to fix, but how to do so is likely beyond the knowledge of anyone that will respond to this thread.

Thanks so much. I have the TS-Tools to mess around with it myself. I contacted Dovetail and their engineering team is looking into it but they had no response to why it's happening now.

I've noticed the same thing. Usually, if you just let the loco run, it seems to sort itself out, (especially once you've rembered to close the cylinder drain ♥♥♥♥♥!).
More mysterious to me is the phenomenon whereby a running loco after a few minutes loses smoke altogether, the exhaust beat disappears, then the wheelbeat sounds disappear. At the same time the keyboard becomes ineffective, (although mouse controls still work), the boiler filling function stops working so that eventually the train is hammering along in complete silence with no smoke.
It happens most frequently with 'Black 5s' and 'Clans' in "free roam" on the West of Scotland lines. Anyone else have this difficulty?

Originally posted by woosmull:

I've noticed the same thing. Usually, if you just let the loco run, it seems to sort itself out, (especially once you've rembered to close the cylinder drain ♥♥♥♥♥!).
More mysterious to me is the phenomenon whereby a running loco after a few minutes loses smoke altogether, the exhaust beat disappears, then the wheelbeat sounds disappear. At the same time the keyboard becomes ineffective, (although mouse controls still work), the boiler filling function stops working so that eventually the train is hammering along in complete silence with no smoke.
It happens most frequently with 'Black 5s' and 'Clans' in "free roam" on the West of Scotland lines. Anyone else have this difficulty?

I've noticed this myself, I wasn't sure if it was just me. It seems to happen if I'm in free look and an AI train goes past. I've no idea what causes it or how to fix either.

Damn that's interesting

Further to my original post - today (20th March), the "shutting" down phenomenon seems to have fixed itself. That's annoying me, because I still have no clue about why it happens from time to time. I did discover how to fix it temporarily. Stop the train, then uncouple the loco. Recouple it, and it's back to normal (including the smoke) - until the next time! I've also noticed that the visible couplings had disappeared throughout the train, although the train stayed together. The HUD indicates the couplings are still intact - but they're invisible on the screen.

Thank you everyone for your feedback. As usual with contacting Dovetail I never heard anything else. Hopefully TS2022 finally fixes all the issues everyone has had throughout the past years.