sv_startsound: sound=2550.
I've read Tommy's guide - it says to check the sounds. No sounds are set to play in the map apart from ones on a big door, which I had tested beforehand. It also says to try developer 3 in the console, which doesn't do anything.
I'm not sure what could be causing the problem. It's something to do with a func_train I've got. The trigger that causes the error is set to start a func_train. This train is a door that slides shut, then on shutting activates a multimanager to set off the main train 3 seconds later.
And with the developer 3 not working, I'm presuming it's part of the same problem with my r_speeds 1 not working either.