So its likely that the various ATS providers had good position data - but entirely dependant on the aircrafts transponder/s. Without that no data at all. There could of course be military radars providing PSR coverage of this area - but that has not been disclosed as yet.
So, if the transponder was inop or disabled, then civilian radar would have been unable to track the aircraft? And we don't know if there was any military coverage?
I'm more and more convinced that they're looking in the wrong place.