RC_OPTIONS ignore receiver failsafe - not working through RCIN port but working through serial ports

I’ve been testing the ignore failsafe option with a FrSky X8R receiver. With RC_OPTIONS = 4, I can get it to ignore the failsafe bit in the receiver when it is plugged into GPS2 (I tested this by making it change modes with the receiver failsafe, without starting the arduplane failsafe timer). However, when I do the same thing with the receiver plugged into the RCIN port, it goes through the arduplane failsafe timer. Any ideas?