There was a bug which was hotfixed two days ago:
I think what happened is that Eudora’s sold minions entered the purchasable / discoverable pool, but since they were not really normal minions, people got one fewer choice than expected. They fixed that by making the minion appear now, but it is still a weird minion, has golden stats but is either golden without the border, or is a new minion altogether, not the regular one, not the golden version, but a mix.
It looks like there may be more which needs to be patched with this hero.
Note that when a hero dies, their minions re-enter the pool of available minions, so this would be more common after Eudora dies.