Engine braking caused engine to Stall.

My apologies if this been asked before or in the wrong section but I have a question for the experienced.

A week ago as I was going 65MPH on a county hiway, my engine stalls on me when I was engine braking. When I saw the sign saying 30MPH in 1/4 miles I engaged my engine brake and slows down then shifted to 9th gear, then attempted to go into 8th, between 9th and 8th (neutral) I heard something rattle from the engine. As I was leaving the small town that is about 2 blocks long I got curious of what that noise was so I tested the engine brake again after getting to 10th then from 10th and slowly engine brake down to 8th. But this time the rattle comes in between 10th and 9th then stalls after I shifted out of 9th gear.
I was able to safely slow down to the shoulder with no power steering. During the stall, all lights still work, nothing flashing, no check engines, nothing. I shut the truck off, let it cycle then start the engine again. It took 3 cranks to start the engine but between those 3 cranks for the engine to turn, the air dryer was purging between each turn, this has never happened before.
When I got to the customer, I checked everything and couldn't find an issue but 1, my AUX PNDB was flashing, when I got back to the hub I replaced the one on the firewall and it went away, now the one under the driver seat just slightly above the batteries is flashing, I replaced that one and it's still flashing.
What could've caused all this?

Forgot to mention that it's a 2014 freightliner cascadia with aprox 755k

 

I'll check on this, thank you.