INR request for an item marked as delivered: Should I ask eBay to step in or let the claim lapse?

[kpmg_keef]

A buyer filed an INR request almost two weeks after his item was marked as "Delivered" and then "Picked Up" and claims his package is nowhere to be found (Shipped through Canada Post Expedited, which then became USPS).
I re-uploaded the tracking number in the claim and sent a nice message explaining the situation, but he still got back to me saying he never received it. It's now stuck in limbo as it's been marked as "Awaiting buyer action" for over two weeks.
It now means all my other payouts are frozen (while I still don't know if I have to set aside the difference to cover an eventual obligatory refund if I "lose").
At this point, would the best solution be to escalate myself / ask eBay to step in, or wait for 30 days overall so it lapses with a "No fault"?
And if it's the second option, could the buyer then file a new one and I'd be stuck in such a loop indefinitely? 
Any insight is appreciated! 

[pjcdn2005]

The buyer cannot open another one once this one has been closed. When did they open it? Have they checked with their post office to see where it was delivered? Apparently there is also a gps record when they scan it.

After opening the claim, if the buyer asks eBay to step in on the 4th day or later ebay should close the claim in your favour.  I haven't ever asked to have a claim closed but I believe that the same thing should happen if you ask ebay to step in.  I'm always wary as a seller to ask ebay to step in.