Well, as you probably know, any flexible filament is a challenge in 3D printers. This is because we push the filament into the hotend with a set of gripping gears and if that filament flexes, then it binds against the walls of the feedpath and very little force actually makes it into pushing down into the nozzle. We also have a couple of less than optimal design aspects of the stock N series, and being honest, I've yet to see technical details that say these concerns are addressed in the pro2 series.
Point being, you generally have to get your hands dirty, and be prepared for minor to major mods on most printers to get them to reliably print flex materials. That's just the facts and circumstances of the material.
So, we begin with previous documentation of this issue in the N series.viewtopic.php?f=4&t=4841&p=28580&hilit=ninjaflex+gap#p28580
The point being, there is a small but known gap in the feedpath, and the bet is, this is actually where your are jamming.
The second part of this is, the stock feeder, sorry, there is a reason they went to upgrades over this from what shipped stock.
There are stages of upgrade and what you are willing to do to make a better feeder.
The first step is just properly adjusting your feeder to better grip the filament by adjusting the gear to the V-groove bearing distance, either by just moving the motor or by shimming to further angle the motor shaft and give even more "bite".viewtopic.php?f=8&t=8497&p=31049&hilit=paper+shim#p31049viewtopic.php?f=4&t=8431&p=30796
Beyond that basic step, stage 2 says replace the non sharp tooth factory drive gear with a much sharper aftermarket version.
This is by far the cheapest and simplest upgrade and makes a huge difference for all filament and works better than stock ever could.viewtopic.php?f=4&t=6193&p=24902&hilit=sharp+tooth#p24902
Beyond that, you have to eliminate the gaps and less than ideal aspects of the feedpath, and the best known option for that is the E3D V6 hotend change and then use Capricorn tubing to make a perfectly smooth and slick path from a Bondtech upgrade feeder. viewtopic.php?f=4&t=4841&p=28580&hilit=ninjaflex+gap#p28586
Also, a new E3D copper nozzle goes a long way to just making this one of the fastest printing Ninjaflex mods I know of. There is only one feeder and hotend that claims to be better, but is not really compatible with the Raise 3D printer just quite yet. https://flexionextruder.com/shop/single/