2014 Ford F-150 auto transmission acting weird

I have a 2014 F-150 Supercab 2WD model with 3.7 V6 and auto transmission with 40,800 miles on it. I had the transmission serviced a couple of weeks ago (1,000 miles ago) at a Ford dealer since it’s still under the 5 year/60K mile powertrain warranty and occasionally after making a hard stop and I press the gas pedal to go, it will stay in neutral for a few seconds then slam into first gear. It happens from time to time. This doesn’t occur if I make a soft stop if that makes sense. I’m curious whether the transmission fluid exchange could have caused this? I’ve not brought it back to the dealer yet. I thought I’d pick yall’s brains first.

If such a thing is possible, give your tranny the old "drop the pan, replace the filter, and refill w/fresh fluid " treatment. That’s where I’d start with that problem. I have an older Ford truck configured with an automatic, and the symptom you are describing is one I had develop about two weeks before it went into the shop for a complete transmission rebuild. However in your case, at 40K miles, unlikely to be necessary. The only other thing I can think of is when my truck’s driveline lube has started to dry up, it will sort of make a bang noise and seem to “jump” into gear after a complete stop, say starting off after waiting for a red light. That’s caused by the slip joint splines in the driveline sticking. Or the limited slip differential needing the friction additive replaced.

this is pretty classic symptom of an underfilled transmission. Have you checked the fluid level? Is it leaving puddles anywhere?

I agree with eddo; it sounds like an underfilled transmission. I’m also pretty certain this one does not have a dipstick so…

If that is the case then it needs to be corrected ASAP or you will be needing a new transmission.