Metro simulator forums

I haven't played a lot of activites yet, but I've encountered a pair of issues in which an AI train that has green light does not move from its position. First on the AI Week activity from Glasgow, I let my train drive itself for a while and when I came back to drive myself, the entire network was stopped because of a train at the depot not moving despite having green light to enter the tunnels. Today I tried A Line Rush Hour in Simvliet and the same thing happened at the end. In both cases I could get the affected trains moving, but, is this due to an error on the activity file? I still don't understand how activity creation works, but I assume if the issue always happen at the same spot with the same train, there must be something wrong with that particular train.