I have a 2018 Ram 1500 Tradesman that I've had since 26k miles. Ever since I've had the truck, it's had a hesitation shifting into 1st/Rev. Delay is about 2 seconds. It's enough time that I can have it shifted into D/R and start to apply throttle and the engine revs to >2000rpms before it engages.
Trans fluid looks normal, no burnt smells. It has the proper amount filled. Under heavy load/accel, trans shifts correctly. Nice firm shifts with or without pulling a trailer (approx 3000lbs loaded).

It doesn't matter whether it's a cold start, or I've been driving all day. I get in, start the truck, drop into D/R, and it takes about 2-3 seconds to engage. Once in gear, there is no issue shifting at all. This doesn't matter from 1st-2nd-etc, or into P or R as long as the truck is running. It's only during the first few moments after the motor has been shut off.

I haven't tested duration after the engine is turned off when the problem happens again, as in if I shut it off, wait 5 mins, and start and try to shift into gear.

Just trying to feel out ideas as to what may be the issue here.

Kori