Looking for advice on how to deal with this:

Cathay is not crediting miles/points for flight AS14 (SAN-DCA) that I took 2 weeks ago. The reason they give is that flight/route doesn't show up in their internal tool, and therefore policy doesn't permit them to credit ("the route in question is simply not eligible for mileage accrual under our current policy").
Just to clarify, this is a completely normal Alaska flight on Alaska metal, they had my number, I was flying on a completely normal first class ticket and the outbound flight (IAD-SAN) credited without any issue.

In normal years, I fly multiple times the diamond threshold so I wouldn't care, but this year these 25 points matter, and CX behavior seems illogical. The agents I can reach won't escalate to somebody who can reply beyond "we can't credit because it's policy". What can I do?