I've encountered this problem a few times with goblin warchanters but now it's happening with the night hag henchmen. Characters encountering the Night Hag aren't given the opportunity to check to see if they can use attack spells before combat engages, they just automatically fail.

 

I'm on an iPad with iOS 9.3.2

If you're talking about all the cards in "chains", those chains don't actually prevent you from using the cards.  First, you try to play the chained card.  Then you make the check.  Then if you succeed, you can play the card.  Otherwise, you can't.