I am having a similar problem setting up failsafe with a Frysky X4RSB connected to a Revo with 16.09 firmware. S-Bus is used for control.
I've followed the instructions in the X4RSB manual for both desired failsafe positions and no pulse. The flight controller behaves the same for both. I've also tried setting the failsafe of the RX using the Taranis TX without success too. I suspect the RX is defaulting to no pulse (for S-Bus) even if desired failsafe positions have been selected.
When the TX is off, the INPUT button on the flight data page is orange and the Receiver Status Quality on the System page is 0%. The receiver activity ActiveChannel is 255. On the Remote Control Input page all inputs are showing max value, in my case 1811. The flightmode always changes to Pos 6 no matter what the failsafe flight mode position is set to.
How can I tell if it has switched to failsafe mode and taken on board the failsafe settings? Should the Remote Control Input reflect the failsafe when failsafe is entered? Similarly, should the Flight Mode Switch position go to the failsafe position?
Any help/guidance on this would be appreciated.
Additional Info: Just attached a servo to channel 1 of the X4RSB. If a desired throttle failsafe setting is set, the servo will go to that position when the TX is switched off. If set to no pulse, the servo does not move when the TX is switched off. However, a lost model sounder that is attached to channel 2 starts to beep. I also tried disconnecting the SBUS line from the Revo whilst the TX and RX were on. Same effect as turning the TX off. My suspicion is that the desired failsafe positions only work for the PPM servo outputs and not the SBUS output on this RX .