Jehovah's Witnesses teach that Jesus is the ransom for all. They also teach that he is Mediator only for the 144K. This causes confusion. They teach that Jesus is mediator of the New Covenant and that the covenant is only between God and the heavenly congregation. So in their view he does not mediate anything for anyone other than the 144K. Jesus propitiates for all. He is intercessor for all. He is not mediator for all.
This seems to cause endless confusion.