I would file away a bit of that area that prevents the RD from sitting flush on the hanger. It likely only needs a mm removed, try to leave smooth transitions.I own a Pivot Les v1 frame.
Since I have the 142/12 dropout kit and unused 9 speed stuff, I'm converting the bike to 1 x 9.
There is a problem wit the Shimano RD-M771 9sp speed derailleur and 142/12 kit-derailleur hanger.
There is not enough room for the derailleur 'bolt-head', only a few mms though.
Is the kit simply incompatible?
Or should I file away some metal from the dropout to make a bit more room?
If I pull the derailleur flush with the hanger it locks up against the protruding metal from the dropout.