Sometimes the charcoal/ heat beads can soak up moisture just from the air....my part pf the question there was "did they maybe catch some from some recent rain/ damp weather".....were they stored good & dry?
It can happen pretty easily.....charcoal is like a sponge for air moisture, so that can be a part of a sluggish burn....
If chilly weather, that will play some part....fuel has to work that much harder to do it's job.....same with the charcoals working up against the wood....if wood is soaked, it must work a lot harder to burn off the moisture, then consume the wood pieces...
If you have dry wood, set that in & pull the dampened pieces....if that can be done without too much trouble.....
Like so, maybe:
(this was for bean pans, but setting the food & the grate out can work for adjusting fuel or other reasons)
The "temp by wireless probe" is at the grate level then?
If so, then some added
lit coal to the burning front may get you up a bit higher.....I'd like to run at 260~285f at the food level for this kind of cook.....trying to aim at 225 well, if your therm or therm placement gives you just 10 degrees misread somehow, you're cooking at near the boiling point of water....things just won't move along fast enough to get done in a reasonable time frame.....
This is what you want to look for....8~9 coals burning or about ready to start....
That
SHOULD get you up above 250~260f & keep things moving along.....don't be worried about the short time it takes to add coals or remove wood (if that's done) the Kettle will recoup very soon after & you'll be motoring along !!!!