Everybody I know that has had issues, has a heel shifter on their bike.
If you want to eliminate any problems going forward, replace with AFTERMARKET parts, it seems Harleys lowest bidder has some soft metal.
btw.....Never had an issue with mine in 45K miles, but I removed the heel shifter as soon as the bike got home and I replaced the linkage with non Harley parts. To be honest, I replaced the linkage because I found some contrast cut parts I liked, after I replaced the parts I found out about the issues and cause
2015 RoadGlide Special
Tuned by Jamie @ Fuel Moto w/Rinehart 2>1