Recently upgraded my Dude Cf to Hope E4’s and the rear calliper just will not fit on any of the available IS post mounts. Hope, Shimano, Canyon & Magura all tried & the best fit I can get with a very sketchy set up of spacers and convex washers is 100% contact on piston 1/2 and 80% on pistons 3/4. Has anyone else had this and sorted it or is it a case of getting a bespoke mount machined !!.