Auto Parking Brake manually set, Auto release, once set, will require some noticeable Throttle to make the Auto Release function.
I use this on up-hill / down hill inclines under slippery conditions to be sure Vehicle does not slide on the surface it stops on when I need to exit the vehicle while engine is running. The Tires' heat causes the loss of traction a short time after stopping from a drive cycle.
Sometimes put in 4wd to have the front wheels locked in park as well, for extra surface Traction. Works for me every time.
Hill holding usually does not hold that much for forward throttle application on 2018 5 L. Depends on the incline angle much of the time.
Good luck.

 

The slip yoke, as JCNorton suggests above. Lubricate with special Ford silicone grease.

 

Thank you again all for replies. Just watched a few videos on the Slip Yoke and seems to be what it feels like. Just a very slight “bump”. Will have to try to get regreased and see if corrects it. Thank you.

 

So it was the Slip Yoke. Just got replaced today under warranty. Thank you all again for input.

 

You can buy a tube of the silicone grease from Ford and do it yourself when it acts up in another 30K miles or so. The yoke is made with a "slippery" type coating on it, but this normally wears, so the greasing become necessary. You'll know exactly what it is when it comes back.