Had similar with a dura ace crank. Known issue, Shimano ignoring it despite the new range actually being marketed as solving the issue. Grey import, retailer doesn’t want to know. I’ve badgered Madison constantly and they suggested I send it back to then via an LBS. I’ve just got to find a localish dealer who doesn’t mind me wandering in and asking them to send it in to Madison when I haven’t bought it from them.
Similar issues in recent years with XT wandering bite point, Leaky XT master cylinder, leaky deore caliper, leaky 785 calipers, leaky GRX caliper to add to Dura Ace issue. Thanks Shimano.