It is said to not assist feed an animal that knows how to eat as you can make them even more stressed and not want to eat (it is also best to have a second set of hands else hurting them is possible, of which I don’t have). Assist feeding an animal that knows how to eat is meant to be a last resort (like they are on deaths door). She was showing no signs (and still isn’t) of illness. No signs of RI or anything else that would cause something like that. She ate twice with me (not in a row) before she decided she didn’t want to eat so I know she could pass food fine and all that. With food in her she was close to 120 grams, without she was about 100 grams but had the typical hatchling build with no fat so more like 20% loss in bodyweight. She was still drinking and not dehydrated either, so illness didn’t make sense and taking her to the vet would have been another source of stress (and pointless as anything that would cause this would have visible symptoms, I didn’t have money for things like an x-ray with no obvious reason either). All things pointed to a fast for whatever reason, as she would still move around her tub at night.
I’m having a similar problem. My girl was hatched last July and hasn’t eaten once on her own. I’ve never seen her strike at me or any of the food. I’ve gone as much as 3 weeks between assist feedings. She’s active in her tub and acts like the rest of the babies. Very curious when I take her out and loves to crawl around. Any suggestions? I’ve tried a pinky mouse, a frozen/thawed mouse and half dead barely moving mouse
Try a live hopper mouse. I also don’t recommend handling until you get them feeding well. If it is for cleaning that is fine, but otherwise don’t.
I’m in the same boat with some of a clutch hatched in
September. Always out and about, only handling whilst cleaning, just no desire to eat. Got a couple of pinkies down them just to get something in them aswell as a rat tail from some of my small rats for the adults, once they are half in they are all eating it themselves just no desire unless assisted.
Lost a bit of weight (10g or so) but now back to weight after first shed. Got some live ASF in the pipeline to try and kickstart something.
My former roommate’s bp (the only bp I’ve lived with and cared for over an extended period of time) would sometimes refuse to eat for as long as 9 or 10 months. But he was a big, robust older boy (15+ years old and quite large, especially for a male), so it was more of an annoyance than a cause for genuine concern. He always maintained good body condition.
Firstly I only uses frozen thawed. (A UK regulation thing but also a preference)
But all the below adults I bought were sold as F/T feeders.-
My longest fast is a year all but a few days for a male after his first mating (He is having a year off now and putting on weight but will only take small ASF Rats)
But my most interesting was an adult female I bought. She didn’t eat for about 6 months from when she arrived I think. I tried everything , warmed dry and warmed wet, Rats, mice, African soft fured rats all sizes, and all in either subdued light or dark.
Eventually I tried a chick and it was immediately taken. Then After a few feeds I got her to strike at the chick but quickly pushed a rat in the way so she would bite that instead by accident… she took that and has had rats ever since when ever offered. Even went on to breed.
Another adult female I bought would not eat until the room was very dark and I let her hang out of the tub to strike and eat, like she was striking from a branch and hanging the food below her as she constricted it.
Another adult female I had to get mated first before she would eat.
Mostly its been adults I have bought that I have had problems with for some reason.
A few hatchlings needed assist feeding for a while but all got the idea eventually.
P.S I find fuzzy ASF rats fermer and easier to assist feed than pink rats. The ASF rats are more solid and easier to assist feed but pink rats are floppy and can explode when assist feeding 
One of my females went just under 5 months without eating. She was 1750 grams and went down to 1450 roughly. Once she started eating again she put her weight back on in about 2-2-1/2 months.