I was in medical billing for some years.
Insurance ALWAYS denys first claims, ALWAYS. Doesn't even matter if they state they cover it in their insurance information list or not.
Doesn't matter if the bill is from a Dr office, hospital, clinic, or other medical entity..........the insurance will deny it.
You just don't hear about it unless it's something unusual, or the hospital is trying to get money up front and not have to deal with your insurance.
Just give it time. Wait 90 days and see if your insurance hasn't taken care of it by then.
You might only have to end up paying only a deductible, if anything.