Detroit DT12 Automated Manual Transmission Issue

by Roger
(Canada)

I recently start with a new company and they gave me a 2016 Cascadia with a dt12 automated. It randomly disengages going down the highway then you have to slow down and pull to the side then it catches in 5th gear then your good for another 500 miles or so. When this happens manual mode doesnt work. There are no gears at all and the engine idles down to 500rpm. Freightliner cant figure it out and im new to automatic trucks and apparently im driving it properly. Has this happened to anyone else? If i only had a 13 speed again....