I'm thinking that is possible that your 'Flying Dragon' may already be an
amphidiploid. If one parent is indeed tetraploid it seems possible that it
may have grown because it had a balanced set of chromosomes, and
everything "worked", the result of that unreduced gamete from I. tectorum that
you've been hoping for. That may be why it is making some pollen.
Of course time will tell, and this may be totally incorrect.
By the way. My personal opinion is that you have a very good shot at
amphidiploid hybrids being fertile. It seems not only probable to me, but