In freeroam I assembled a formation of two RSR class 37 locomotives with three LMC Mk2 coaches in between them. When coupled together the train is unable to release brakes with the brake pipe stuck at about 20psi, even if I try manually releasing brakes in both lead and trailing engines the brakes stay stuck on. Both locomotives have their brake modes correctly set to Air Passenger. Could it be down to the fact that the locos refuse to connect their main reservoir (yellow pipe) together to the coaching stock? Between 37 and coaches only the red main brake pipe connects. I can only get a brake release by closing the brake pipe air valve on the trailing 37 to effectively isolate it from the rest of the train BUT its brakes still are stuck on and refuse to release resulting in it being very hard and sluggish to drive since the trailing loco drags. The formation is set up like this: Lead loco, air passenger, lead cab set up as normal with brake valve, trailing cab brake valve in shut down Mk2 coaches X3 Trailing loco, air passenger, both cab brake valves set to shut down position.
I think the Mk2 coaches are bugged in free roam along with some other trains after the update a few weeks ago. I didn't have any problems dragging the coaches when I tried it, but I was unable to couple the coaches together in free roam. I had to make a formation in formation designer and spawn that. Not sure why we are getting different bugs instead of the same bugs. Hopefully whenever the next update comes they will fix things.
The Mk2s did have coupling issues. For whatever reason they only attach when the buckeye coupler is set to "locked" as opposed to "unlocked" for me.
Also I found the source of the issue. It seems like DTG scripted it so that if AWS is not isolated the brakes lock even if the change ends switch is turned to the OFF position as per reality. Usually the AWS isolation switch would never be isolated, drivers normally use the Change Ends switch to engage AWS in the lead cab however the TSW 37 is scripted differently so that the isolation handle has to be completely isolated in order to allow brake control.