Here another player with a recent buyed jtv89f with the same plinky noise at the 6 string when playing with palm muting and some distorsion, have to say that in some different modelling I can heard it in the 5th more than the 6th.
In addition I can notice (as another user mentioned as well), that the volume of the 6th sounds higher than others with both magnetics and modelling. Also I noticed always another metallic sound on the 6th string.
I'm very annoyed seeing the experiències that people had here with line 6 support... The store doesn't accept return and all this sucks a lot. Will open a ticket but don't think it will solve anything.