I just tried to build an Eldrazi black mill deck (more for fun than functionality), and I noticed that when I fight a “colorless” Planeswalker in the story, like Angel’s Tomb or the Guardians of Meletis, ingest doesn’t do anything. I don’t know if it was supposed to be like this, but it does make Eldrazi decks useless against them.
And as for the second bug, I’ve seen that when no more gem matches can be made and it reshuffles them, if there is a 3+ gem match made, it freezes the gem board so you are forced to quit.
While not impossible or game-breaking, they are both annoying and would make the game better without them.