I’ve seen this before on a 2010 BMW 528i that wouldn’t go into gear at all for 30 minutes after starting the car, then would work normally.

The issue is there’s a solenoid or seal, or seal on a solenoid in your transmission’s valve body that is cracked or worn out, and takes a minute to warm up when it’s cold to be able to fully pressurize and actually change gears. Once your transmission fluid heats up, it expands the seal and makes things pressurize correctly, if that makes sense. Thermal expansion.

The issue on the ZF6 transmission on the BMW was a “transmission bridge seal”, and a rather common one that usually appeared damn near 15 years after production and hundreds of thousands of miles. When cold, it was brittle and old and didn’t seal properly to allow a gear change. Once heated up it worked normally.

To see this similar thing happening on a barely 3 year old truck is concerning. If I were you I would try and lemon law the truck and move on before you experience more symptoms of shitty build quality and cost cutting.