Work In Progress..
- '18 CX-9 Signature
If you take it back and they still deny the noise...then you'll need to make a choice. Keep trying until the 12 month bumper to bumper is expired at which point they'll want you to pay. Or take it to a local mech now and pay him to diagnose only/not fix what's wrong with it then take it back to dealer and make them fix it.
I don't think it works like that.. if you open a claim while you're within warranty, and the claim/ticket is still open when your warranty expires, they don't just drop your claim. I could be wrong, but I really hope I'm not because that's really f'd up if dealers/manufacturers are allowed to do that.
Diagnosing elsewhere seems like a good idea, but it depends on the dealership too. Some may be adamant about diagnosing the problem themselves because it puts money in their pockets. Some may also require that diagnosis be done by the dealership for a warranty issue because they don't want to be on the hook if the part/repair doesn't fix the problem.