The second quest card from The Siege of Annuminas contains text that reads "..... Forced: After the players have committed characters to the quest, the highest Attack enemy in the staging area makes an attack against each player in turn order. If no attacks are made in this way, reveal the top card of the encounter deck. ....".

If there is a side quest in play, is this aspect of the original quest card ignored? Since the side quest takes precedence over the original quest card during the quest phase, it might seem that text related to the quest phase would get overridden in this case, but that seems like too much of a break for this game to give. Thoughts?

If it's saying "after the players have committed characters to THE quest" you'll still be resolving that effect, because the card is not referring to a specific quest card. If it said "after the players have committed characters to THIS quest" I guess you'd be able to use a side quest to get around that.

3 hours ago, Orcstalker said:

Since the side quest takes precedence over the original quest card during the quest phase,

The text of the top card of the quest deck is still active even when the active quest is a side quest and, as said by GrandSpleen, since it says "commited characters to THE quest" it wouldn't matter if it's the "main" quest or a side one.