2019 Mack Anthem MP8 - Transmission Hunting and Hard Shifting (mDrive)

The mDrive 12-speed on my Anthem has started acting very strange. When accelerating from a stop, it skips gears violently and sometimes 'hunts' between 7th and 8th. Occasionally it won't even find a gear and sits in neutral until I restart the truck. No active codes on the dash, but when I scanned it, I saw 'Incorrect Gear Ratio'. I've checked the air supply to the transmission and it's holding a steady 120 psi. The truck has 380k miles, transmission fluid was changed at 300k.