Updated 01/21/2024

There are SEVERAL things that can contribute to pellets not successfully burning.
Here is a list of the usual culprits:

(in order from most to least common)

1. You're using a standard household extension cord.
 

The manual states that any extension cord (or "lead") used, should be:
- 14 gauge (up to 25′ long)
- 12 gauge (up to 50′ long)

The extension cords commonly used in US homes, that people consider "heavy-duty" are usually 16 or even 18 gauge. And are below the specs required for successful operation of the Ninja Woodfire.

Think of the pellet ignition element like a small space heater. They usually have shorter, stiffer, (and usually non-removable) power cords. Because they require heavier loads than other common household electric devices.

One of the best and most thorough reviews / explanations i've found of the
Ninja Woodfire can be found at Gear Diary

​2. User error.

Pressing the wrong, or wrong sequence of buttons can also lead to ignition failure. 
In smoke mode, you DO NOT NEED TO PRESS THE WOODFIRE BUTTON at the beginning of a cook. If you do, you've most likely turned ignition off.

The ONLY time you need to press the woodfire button in smoke mode is IF you've refilled the pellet hopper and need to "light" the new batch. And in this case, you have to hold the woodfire button down for 4-5 seconds for it to engage.

3. Your Pellets have been compromised.

This could be a manufacturing defect, or simply a lower quality product.
Or they could have been exposed to moisture during transport or storage.

Always keep your pellets out of direct, prolonged contact with the elements.
Store them in a well-protected area (indoors if possible) and in some sort of
resealable container. 

SIDE NOTE: I don't know that this has to do specifically with pellets being compromised. But MANY people claim to have better pellet performance after microwaving a scoops-worth of pellets on a paper towel for 30 seconds before putting them into the woodfire.

Some people claim this "dries them out." I'm not sure whether or not that's the case, or if it simply gets them out closer to the combustion point. But it seems to help people. So, I'm not going to argue with them. : )

4. Air flow.

Whether you're using a Ninja Woodfire, full size, pellet smoker, a traditional wood smoker, or even a basic charcoal grill, one of the most common stumbling points is AIR FLOW! If you don't have sufficient air flow, your fuel source won't perform as it should.

There are three primary possible causes for poor air flow in the Ninja Woodfire:

a. TOO MUCH FOOD!
If you've stuffed too much food into it. Or if a single item (like a large roast or
intact whole turkey) blocks the fan or impedes air flow, your pellets may not light or stay lit for the duration of the cook.

b, WIND!
If wind or a strong breeze is moving directly into the exhaust vent of the Woodfire
it can possibly choke out your pellets.

c. POOR PLACEMENT!
Similar to the issue with wind. if your Woodfire is placed too close to a wall or in a corner, there may be an issue where it can't properly expel the exhaust.  

5. A "Glitch" in the device.

This should probably be higher up in the list, as it's a fairly common situation. But it's harder to diagnose. So that will keep it here at the bottom of our list.

For a variety of reasons, sometimes the auto ignition (and sometimes even the manual ignition) will fail to engage. If this happens to you, the most effective solution is to simply turn the Woodfire off, unplug it from the wall, wait about 30 seconds (a couple of minutes is best, if you have the patience) plug it back in, and re-start your cook.
Unless your cooker is indeed faulty, this will get things back on track!