Hi there,
I was just double-checking this, and the algorithm dropdown doesn't need to be manually set since it automatically changes to the value of the algorithm in the header.
But while testing this I actually got it to verify; not sure what was different each time since I could have sworn I tried both the public key and the certificate with and without the PEM headers (looks like the PEM headers are definitely necessary), but maybe I was using the wrong key or something.
Anyway thanks for looking into this!