I spawned at the Pruszkow post just now, and I see that absolutely everything is backed up (INT1) (while there are no players around in other posts or trains).
There is a defective piece of track it seems that is showing a 'green sign', but it doesn't start from a green sign, and it seems nothing can be done with it.
Aside from that, everything is backed up on the side of Warszawa Wlochy, (unsure whether directly from Pruszkow, but definitely from Jozefinow):
After checking the server map, it seems that almost everything between Pruszkow and multiple Warsawa stations is standing still.
No idea if this is a bug or something went wrong that is supposed to be able to go wrong, but thought I'd report it :)
EDIT: I swapped to Wwa Wlochy, and it seems the traffic really is getting stuck between Wwa Wlochy and WWa Zachodnia: