While playing a game of Pioneer on arena, I resolved Invasion of Alara which exiled 2 copies of Bramble Familiar. When prompted to cast one of the two cards, I selected a Bramble Familiar and it then did not give me the option for which half of the card to cast and instead put it straight into exile as if it was not cast and the other card went into my hand. There were no effects in play that would have prevented me from casting the Bramble Familiar or its adventure Fetch Quest.

The correct behavior, which the game previously handled correctly prior to the Omenpaths prepatch, would be on resolution of the Invasion of Alara entering trigger I would be allowed to cast the Fetch Quest adventure spell from exile without paying its mana cost. The only explanation I can think of for this sudden change would be the prepatch which was installed just before playing this match today, where the game was working prior to that install.

Instructions for recreating:
Start a match of Pioneer
Cast Invasion of Alara
Choose to cast a copy of Bramble Familiar // Fetch Quest from the Invasion's ability
Result: Neither half of the Bramble Familiar // Fetch Quest is cast by the ability, where it should prompt the user to select which half of the spell they would like to cast