Ive narrowed down a loud knock/tick on my 2017 Hemi RAM...it happens like this:
If the truck sat, say overnight, then I start it just to move it a short distance (think: to the other side of my driveway), then shut it down....if I start it again within an hour or two, it will make a fairly loud knocking noise for 3 seconds at startup. Not a lifter tick, IMHO....its a deeper tone.
If I: drive it longer before shutting down (as simple as driving through the roundabout at the end of our street) OR I let it sit for an extended period again, the loud knock does not occur at startup.
I have no idea WHY it does it, but over on RAMForum it seems to be a common thing in this exact scenario. Im not sure if that is what the manual is referring to or not as a "short distance". There are theories as to what it is but I dont think anyone knows for sure (probably not even Mopar).