I was doing some research regarding dual passports. Apparently the advice is *not* to switch between them for your ESTAs. That is, if you have been getting ESTAs in passport #1, don’t switch to passport #2!
The reason for telling the above is that someone switched and their ESTA was pending/denied. In their case they went to the embassy/consulate, who made a note on file, and the ETSA was then approved.
So maybe in your case a visit to the embassy or consulate might be worthwhile? It might be a case of someone unlocking the ETSA once they have the additional information.