Yes, I suppose it is possible that someone told them the claim would be denied, but until it is submitted you cannot know for sure.
Do you have written proof that you won the appeal? If so, give a copy to the supply company so they can submit that along with the claim.
You also should be able to ask for a case manager or you may already have one (the person who handled the appeal) See if such a person exists and if so try working with them too.
Calling the state insurance commissioners office (or threatening to turn them into the commissioner office) is also a good thing to do. There is no reason why you shouldn't be able to resolve this - it still just seems to me like maybe the appeal information didn't get filed correctly and the claims people do not have the correct information at their fingertips.
Do you have written proof that you won the appeal? If so, give a copy to the supply company so they can submit that along with the claim.
You also should be able to ask for a case manager or you may already have one (the person who handled the appeal) See if such a person exists and if so try working with them too.
Calling the state insurance commissioners office (or threatening to turn them into the commissioner office) is also a good thing to do. There is no reason why you shouldn't be able to resolve this - it still just seems to me like maybe the appeal information didn't get filed correctly and the claims people do not have the correct information at their fingertips.