Yup, right before Stonebridge Park. I first did this with the 377 and was stuck there for a good 15 minutes trying to get by until I thought about tricking the game by sitting in a seat and switching through. Idk why its there, DTG said they'll only block people from entering the tunnels on foot.
I think it’s a bug. You could put this video in a bug report here on the forum to show the invisible wall in action, if you don’t mind that is.