Some older engines, made before 1950 will have problems with uncoupling tracks, and your 1122 switches. They should be OK with 1121 switches, but that won't help you.
The problem is caused by drive gears hitting obstructions built into the newer tracks.
I wish I could tell you which ones have problems. Off the top of my head, I don't recall, other than 1654 and perhaps the 1656, which are both postwar engines.