VNL 780 2015 - I-Shift problem maybe transmission.

The problem I'm having is when I select gear into "Drive" from Neutral it would go straight into 5th gear but I don't hear the gear switch. After this happens I go into Reverse-1 and not even a backup sound from the rear Reverse speaker. When Pressing the manual (+/-) buttons it would sometimes switch into gear and start moving. When I start slowing down and coming to a complete stop it would go into 5th gear again and just gets stuck there, stepping on the pedal doesn't do anything until I switch around gears manually going from 5th to 4th etc... I can see the gears switching on the dashboard but doesn't feel like its switching. When I switch into Neutral and throttle the RPM would move normally. When I'm in Drive and the dashboard is showing 5th gear, I hit the throttle and RPM doesn't move until I switch around gears up and down (it sometimes takes a while), when I actually hear the gear switch into gear then the RPM moves and the truck drives.

Please if anyone has experienced this before or is familiar with this problem let me know what it could be. I was able to tow it to Volvo but they are backed up for 6 weeks and won't touch my truck if its something major. I still have warranty on my transmission, if the tranny is the problem then I guess I would have to wait.

My truck is D13 2015 with 560k miles.

 

No fault codes on the dashboard at all, the dealer said that when they scanned it it showed a gearbox code, they didn't tell me much. they just said it could be anything, they need to further diagnose it before giving any assumptions.