Hostage Taker undermining Sangrite Overlords [Investigating]

I just had a game where the opposing AI used Hostage Taker to steal Avaricious Dragon from my board. A few turns later it had been played to their side and when I activated Sangrite Overlords it only Fetched a single Avaricious Dragon rather than 3 copies(I have a Level 56 Sarkhan Unbroken). I had no other valid targets, to be clear.
I had the space on hand and there's no reason this should happen except for the fact that an Avaricious Dragon of mine was currently on my opponents side. 

By my understanding of how deck generation works in relation to your 10 card 'deck' there's no reason them owning a copy should change the fact that there is no limit of duplicates of that one card in my 'deck' and even if it were to have an impact I summoned 2 less than I should have...

//Edited Title - Tombstone