RE: Single or dual conversion?
I'm not familiar with your TX--so pardon me if this is way off:
Is the TX set to run in SPCM mode?
I've had that problem before. I use regular FM PPM RXs in all my planes. But, my TX can transmit in SPCM or PPM (FM). If I forget to turn the radio to PPM when I first set up a plane, it will act exactly as you describe. Everything jumps for a second and then I got nothing.
As soon as I remember--I switch the TX to PPM and then it all works perfectly.