Heres my own experience of dealing with an immobiliser that shat itself, FWIW not a full solution as your hardware is different but I hope it can help you
My 2010 990R immobilizer went, and no amount of reprogramming etc would sort it. KTM were as useful as a glass hammer, and suggested I change the lot....barrel, RFID antennae, ECU, keys, fuel flaps, under seat key barrell, I didnt even ask the price. Oh, plus it meant I would get a new immobiliser ready to go belly up in Bolivia. Bollox to that
We figured the pre 2008 models had no immobiliser. So we fitted a 2007 ECU we got cheap. Then loaded up 2007 map (this wont look for an immobiliser signal, not sure if there is a RC8 model with no immo that you can do the same trick with.
We got it running, had some issues with the TPS`s so we changed those also.
Now we just used tuneECU to copy and paste the 2010 map tables into the 2007 map file, reaload back up, and bingo!
Good luck mate!