now 99% of the time kids with a fleece allergy do NOT have an allergy to the fleece it self at all. What happens is fleece is polyester, which is in a LOT of things, it is essentially plastic. So to have an allergy to that would be a MAJOR allergy and one that would effect a HUGE amount of your life. It is just SO rare to see more than one child with it for real on this board would be a slim to none chance.
Now what USUALLY is the problem, being plastic and non absorbant fleece just holds residue on top of it, so any chemicals left on the fleece are in direct contact with a VERY sensitve area. Fleece sensitivity looks like a burn, sun burn or worse if it is worse. Why? because it IS a chemical burn, from whatever it is that your using on your diapers that isn't getting rinsed clean enough for your child.
Now kids vary in sensitivity some kids you can rinse out enough (even if you have to triple rinse) and make fleece okay again, SOME kids you can NEVER get the fleece clean enough. Most of the time the residue on fleece wouldn't bother kids (or adults) but this is a very sensitive area and high acid in the urine can really create problems. SO it is possible that your child can not use fleece, it is also possible that they can and it just needs to be rinsed more. But the chance that they have a fleece allergy is slim VERY slim. Some women can't use anything but 100% cotton panties because of irritation, this is kinda the same thing yk?
Fleece liners cause less of a problem than pocket diapers with fleece sensitivities because they are rinsed cleaner over all. while I know pocket diapers come clean when spinning out in the washer they don't get the benifit of the water flowing through them to really rinse the fleece because of the PUL, water can't flow through it, to rinse and spin it. Especially if it happens to fall where the fleece is on the inside of the PUL and the PUL is against the washer drum, then your fleece will feel really wet too.
So my suggestion to you is to hand rinse your pocket diapers (after they have been washed in the washer) a few times before using them again and try it. If they are the problem you will notice it. I have more problems with pocket diapers than I do with fleece liners or fleece lined fitteds (because of the rinse factor) Joe has NO problems with fleece as long as it is rinsed well, if it isn't, he gets the burn.
Also if your child has a fleece 'allergy' they will also be allergic to PUL and any poly clothing (which there is a lot of) most likey your car seats have poly in them, as well as a ton of their toys. So fleece allergies are very VERY rare. But the sensitivity (especially when applied to the area we are speaking of) is a lot more common.
Good luck! I hope things work out for you!