I'm running a GX Eagle drivetrain on my Sentinel, and shifting has gotten a bit rough in the last month or so. I built the bike in March and rode it through the summer averaging 2 days or so per week, so got some decent mileage on the drivetrain. Anywho, went to swap the chain to a new KMC 12 speed X12, and it isn't meshing properly with the teeth in the 2 largest cogs on the cassette, riding up on top of the teeth rather rather than engaging them. It's also hanging up on some (apparently) bent teeth on the smaller cogs as well. I checked the original GX chain that I was hoping to replace, and it's still showing less than 0.50 on my chain checker, which to me is the threshold for 11 and 12 speed chains being worn. Is it possible that the GX cassette is just made of shit materials and is already worn with only ~600 miles on it? Or are there issues with KMC's 12 speed chains? Curious if any of you guys have run into similar issues.