It works as I would expect. With EXPTIP set to SWITCH, I connect a FS300 switch with a TRS cable, and set PSW to RNG.
When I press and hold the switch it shows BRAKE. If I press and quickly release, it shows BRAKE briefly and then toggles between FAST and SLOW. Maybe you are confusing yourself by holding down the switch too long – it has a sort of dual function which takes a little getting used to.
