Claim for appendectomy was denied after request for additional info

I had an appendectomy in April after being diagnosed with acute appendicitis. Everything went smoothly, but spent a night in the hospital before the surgery. Since then, I’ve been getting a trickle of medical bills and I have paid them as they have come in. I just checked my insurance portal (Aetna) and saw that the procedure itself and the services provided at one of the 2 hospitals I went to (originally went to ER, got diagnosed and then transferred to the other hospital for surgery. They are just different campuses of the same hospital) were denied.

When I look at my explanation of benefits, it says “You don’t owe this amount. We denied this charge. We previously asked you or your provider for more information. We didn’t get it. Refer to the prior explanation of benefits”, but under the claim it also says I may owe $38,000. I haven’t received any bill for this from the hospital, but insurance only denied it 3 days ago. Should I just wait and see if I get a bill from the hospital? Should I clarify exactly why the claim was denied by insurance? Should I check with the hospital to see if they responded to any requests for additional information?

I really don’t want to be in a situation where I actually end up on the hook for $38k something that definitely should be covered. What should my first step be?