thanks, ...i'll try moving them closer next time I try to re-bind a receiver ..although they were about 12" apart ..but perhaps touching would be better.
I actually found a solution, it doesn't solve the issue, but it is a solution.

I have the same type of receiver in another car, I tried and successfully was able to bind another receiver that was previously being used. AND I took the problem receiver and re-bound it w/ no issue to a different controller. The receiver I was having trouble linking to my 4PX and couldn't bind was easily able to bind w/ a cheaper Futaba controller w/ no issue. Odd ...but after playing some musical chairs w/ my receivers they are all bound.