2018 5.3 Transmission intermittent issues

[Hunter Swan]

So I went on a 12 hour drive the other day and had some really strange transmission issues arise. 
 

About 8 hours in at one of my fuel stops, when I shifted to park the gear indicator read that I was in L1 (but the truck was actually in park, had no movement and didn’t roll). Then when I got back in to drive, the gear indicator didn’t show the box around drive (and wouldn’t actually engage drive to move the truck) but oddly when I shifted to L1 the truck went in to gear and would move. 
 

Happened again about 2 hours after that. 
 

Then today I went on a quick 40 minute drive and the same thing happened when I pulled into a store to grab some food. 
 

Truck drives fine otherwise. 
 

Any idea what could be causing the issue?

[rav3]

How many miles on it? Which transmission? Has transmission ever been serviced? Fluid level ok? Have you done the pill flip or replace the transmission thermostat? 

[Hunter Swan]

37 minutes ago, rav3 said:

How many miles on it? Which transmission? Has transmission ever been serviced? Fluid level ok? Have you done the pill flip or replace the transmission thermostat? 

153k

6 speed not sure of the exact model

unknown if it’s been serviced, bought it used about 2 months ago

fluid level is a smidge high after just checking it. 
I haven’t done the pill flip or the thermostat. Don’t know what the pill flip is honestly 

[rav3]

https://youtu.be/n2FxBMHStHQ

[rlcole321]

It takes an electrical issue to display the incorrect gear, also the trans is (Mostly) electrically controlled, have it service with the pan removed and new filter, and they can check wiring harness.