Ok time to throw out my 25 cents worth. First off I think I have a unique advantage here. First off I have been flying R/C for 36 years. So I have used all types of systems from the old AM stuff to FM, FM narrow band, PCM and now SS. I have also been professionally building RF equipment for 15 years and currently build aircraft antennas of all frequencies that end up on military aircraft. I at times work with our R&D department not only building antennas but building test rigs that go into the chambers to simulate what affect the aircraft will have on said antenna.

That being said to a certain point I agree with Dirtybird and think that Ace has a great perspective on what is happening. For ignition generated RF to swamp a 2.4 RX it would have to be a significant amount of power. Most ignitions draw approx 1 amp at full throttle. The input power going into the ignition just would not support enough power to swamp the RX. Even if it did, the system would go into Failsafe. What we are seeing is glitching. This clearly means that the stray RF is coming in somewhere other then the RX. The signal wire of any servo lead can act as an antenna and transmit RF into the servo. This is what we are seeing. This usually only happens when something is amiss with the ignition. A loose cap, chaffed grounding braid on the wire, too large a gap on the cap seam could all cause this issue. IMO as long as the ignition is working as designed then there should be no way it can create issues with RF.