No Mutant Is an Island - S5-E4
Other mistake: When Killgrave is standing in front of the projector, the projector image is cast onto his person matched color for color, except for when his own image in his true purple-skinned form appears and the image cast onto him maintains a normal flesh color. (00:11:20)







Answer: Chris Potter, the original Gambit voice actor, did indeed quit the role in the 4th season. His last episode was The Phalanx Covenant Part 1 so it seems reasonable that Fox would limit the use of the character even though it was recast. It doesn't appear that Potter left the role due to animosity, he stated in an interview that he wished to play Gambit in the first live action X-Men film.
BaconIsMyBFF