Desync/race condition right after joining as dispatcher.
If you join as a dispatcher and there were outbound route(s) created by AI, there is a possibility of encountering permanent red signal that can not be cleared (as far as I tried) or "remnants" of a route. The only solution that worked is to leave and join again. Then it's fixed. (if it did not repeat again). Reproducing this issue is very difficult. I encountered this issue 3 times today, then started to record gameplay, purposely joined at the right time(as I think it is after train begin to leave the station) and reproduced it 2 times out of 20.
red.mp4
route.mp4
red_log.txt
route_log.txt