Eyeballing it with the chain off it doesn’t look too far out, but it’s definitely sitting beyond the 11t.
Only error message I get is if the high limit is too tight and it prevents the mech from doing the little overshift wiggle. The limit screws don’t appear to alter the index point with Di2, just stop the chain from dropping off the cassette.
Unplugged everything and left it for a few hours, but it hasn’t forgotten any settings or ‘reset’. Assume there’s another wee battery in there somewhere? Ran the crash reset mode but that doesn’t fix anything.
Tried a different wheel (Pro 4) with same result. It’s almost as if the driveside end cap is a few mm too wide, or the mech hanger is a few mm too thick. Either way I think it’s a shop job :(