Ultrashift 10 speed auto sometimes won't go into gear

So on my Freightliner Cascadia for the past few days ive been having issues.going into gear after j have been idling for several minutes in drive. I was at a traffic light waiting for the green light in drive with brakes released and the truck showed a flashing check transmission light and the gear display flashed the letter "F" and I think "N" I was able to get going after switching Neutral then drive and was thankful to keep going. Today after fueling I go in My truck to restart the truck and when I try to put it in drive it acts up again. I play with the shifter and shut off the truck a couple times and then it goes into gear.

This truck is a former Tyson Foods truck and Tyson Foods shop mechanic told me it could be the XY shifter causing the issue. He said I may need to tap on the transmission shifter underneath the transmission to get it to go in gear and it could need replacement.
If it's wore out.
Anyone else any ideas?
Also it is not pulling loads good. Could it be my clutch going out and being weak?
Thanks for any feedback.

 

It also says "88" on the gear display

 

Also code 27, think that means clutch disengagement. Maybe I need a clutch

 

It has 508k this is a 2013. It shifts alright but like I said from a stop to a start sometimes it won't go. Just "F" and "N"
And it showed code 27. This sucks.