I don't exactly know if this is a bug or not, but all modded characters can vore characters that have eaten 2 or more other units when the non-modded units cannot. Another bug which I am experiencing, is when loaded into a battle, modded characters will disappear and just leave their shadows behind, which I believe other people have had issues with. I do not use the ARK mod so I don't believe that she is the issue.
In regards to the two prey swallow thing, I believe the method for setting the max amount a unit can swallow at once changed, and I didn't catch it until after I published this version. I'll double check how this is working in the current version but for now it shouldn't ruin any units since capacity is still taken into account.
For the sprite disappear thing, that was a bug related to memory when you install a lot of mods at once. It was a bug that existed in the unmodded state of the game.