I haven't tested these with the latest beta yet, so some may have already been fixed.
Magus of the Moon /
Spreading Seas don't work correctly (alone and or in combination). While they will turn lands into Mountains or Islands, the land will retain their other abilities.
The computer keeps playing
Whitemane Lion when it has no creatures on the battlefield.
Stonecloaker exiles two cards in graveyard(s) and does not return a creature to my hand.
The computer keeps activating the abilities of
Jodah's Avenger, regardless of the situation, every turn. The computer had enchanted its
Jodah's Avenger with
Dust Corona and then gave it protection from red.
Porphyry Nodes does not get destroyed if there are no creatures on the battlefield during upkeep.
When multiple creatures block
Evil Eye of Urborg, only one is destroyed and the other(s) deal combat damage to
Evil Eye of Urborg.
The computer keeps trying to
Norin the Wary or to enchant
Norin the Wary. I destroyed it once with
Kaervek the Merciless (it was getting really annoying), it was put into the graveyard, and then it was returned to the battlefield (from the graveyard) at the end of the turn.