Need advice, no traction on slick road whatsoever.

Hello.
I've been driving trucks for over 20 years (most of it local though), but have never experienced something like this.
The truck: I recently got back to the OTR and picked up 2016 Freightliner Cascadia with auto transmission.
I woke up this morning in Petro, Laramie, WY and hit the road going east being about 73k lbs on gross. It was snowing and the road was somewhat covered in snow so I would say that it was a bit slick driving on the packed snow/ice. The plower trucks were going throwing dirt on the road. So here what's happened:
The truck was doing fine till I got to an upgrade. It started loosing speed dramastically like it has no power at all. When it got down to like 15mph I thought that it is traction control holds the power back. Sure thing - as soon as I hit disable ATC button - got power back. But all what it was doing is spinning tires and not really picking up speed, at that time I was crawling at about 2-3 mph, so I was doing that, trying to pick up some speed till I got to a some bridge where it stopped at all. I could not make it go forward. As soon as I hit throttle - tires spin forward and truck rolls backwards. So I had to back it up behind a bridge to a shoulder. I slided the trailer tandems all the way back to put as much weight on a tractor tandems. Also engaged differential lock. With all that done I hit the road again, I don't know if any of that helped, bit it still was spinning the tires and slowly crawling up the hill. I tried to stay off to the side so I can get some traction from the shoulder. Anyway, I pretty much had to crawl like that to the top of that hill. All other trucks were passing me with no problems for them.
So can anybody shed some light for me on what is wrong with that truck? This is new to me truck and I am not really familiar with some systems in it. For example, it has ECAS (electronically controlled air suspension) which seems to be not working. I have Check ECAS light on dash and remote control is dead - don't do nothing. Could it be it?

 

Tires look fairly new - very good thread. Green Max CDH100

 

Looks like date code is 3420. And no, not super singles. Regular double tire setup. 295-75 r22.5