Apologies for taking longer than anticipated, but I have attached the save. Only mod used is Automatic Coupler. You will want to look at the Southeast corner, specifically the railyard-in-progress right next to a large iron refinery. It is disconnected from the main rail line. It can be reproduced b...

Yes, I will post the save and a guide to reproducing it later tonight. I have gotten it to happen 3-4 times now, though I am the only one (of three total) on the server affected. Although the other two are on the same network, so that may be a factor as well. If I find a solution I will post it, and...

GotLag, I just wanted to say that this mod is fantastic. It's the only working automatic coupler mod I can find and it makes trains so much more interesting. I've also just run into a multiplayer desync involving a train coupling to a few cars (in my case, two locomotives coupling to four item cars)...