It's to do with MOM mod not this one I think, do you have a metro depot connected to the line?

Thanks for you comment, what is the MOM mod? And what exactly is a metro depot supposed to be though? There is no such thing in the game.

MOM -> Metro Overhaul Mod :D https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=816260433

This has done this for quite some time. Probably a combo of the 2 mods not quite working together right. A workaround is just saving and reloading the game and the new depot then show up on the list.

I think I've narrowed it down.I have a glitch my metro lines are showing trains going round but no passengers boarding! Also my monorail won't connect unless you do it by road only connection.Previously I could connect using "rail" only.I do like your mod but I'm going to have to unsubscribe until it's sorted.By the way buses and trams seem "normal".I love seeing the buses etc going round picking up passengers .Thanks.

I had same problem with metro trains spawning and immidiately despawning - IPT2 installed, no MOM. What I noticed, that eventually I replaced all vanilla metro stations with workshop ones, and some of them had unusual signs in the name. I renamed all the stations with only letters and numbers used and spawning works again