XX1 - Chain Rubb on 12 & 11

[Bat-ass]

First make sure the barrel adjuster is tuned in correctly..... not too sensitive to up shifts and not too sensitive to down shifts.. if that makes sense? when its too sensitive to up shifts it doesnt cause too many problems at the bigger end of the cassette, but at 11,12,13 it sometimes wants to ghost shift...

 

and definetly check for bent hanger.

Its got nothing to do with front crank / chainrings