Just to circle back and provide an update!!
Using a Taranis, Super X using SBUS, and an X8R receiver, FAILSAFE WORKS PERFECTLY!!! Yes, using SBUS.
Steps:
1. Setup everything possible in Companion9x you normally want. Set Receiver mode to D16 for the X8R, and Ch1 thru Ch16.
2. Click on Failsafe tab and select Custom.
3. Put Ch 6 on 100% (this is the rub in my case as even though I did it, it did not work).
4. Save EEPROM to radio.
5. Bind RX and TX together. DO NOT SET ANY FAILSAFE ON RX!!!
6. Now, to fix it up! On the TX, go to the Failsafe setup. It will be in custom already, so skip to SET and press ENT.
7. Minus down to Ch6. If your's is like mine was, it was not at +100%. Press ENT
8. Now move your RTH switch you setup on the radio to the RTH position and make sure it is showing +100% on the bar.
9. Press and hold ENT to commit changes.
10. Exit back to main screen. Power cycle TX and RX and test.
Now if I read the model into Companion9x, it all looks fine. If I make any changes and write to the EEPROM, everything is updated EXCEPT the failsafe. After writing to your Taranis each time, repeat steps 6 thru 10 and you will be set. Even if Ch6 shows 100% after a write, still repeat steps and save or it won't work. Must be a bug in Companion9x?
Hope this helps someone! BTW, I am using Super X with Stella, as well as the FrSky 4 CH SBUS Decoder. ALL 16 Channels work on SBUS, along with Failsafe!!
Regards,
~T.J.