I seem to remember a supposed fix that involved a new seal and new spacer, but I'm not having any luck finding where I read that. That was for the Twin Cam RushedMore bikes, still haven't seen a fix for the M8 bikes. There are a lot of very PO'ed folks on other forums with 2017 and 2018 bikes experiencing severe migration issues, one I remember reading about would transfer 20 ounces from the trans to the primary in just a few hundred miles.
Sure am glad Harley did all those millions of miles of testing. I'm guessing those were virtual test miles, not actual riding of production level bikes by real people. Some people think they can assign everything to a computer program these days. "It works on paper (monitor)" is a common comeback to an issue. It might be a good answer if we only used virtual products, but I always found those virtual rides to be less than satisfying. After all that riding I found myself still at the starting point.
Jerry