Yewstance

I have barely played since the patch, but in case it hasn't changed...
 
Try to play a spell that has the 'lock' symbol on it. Click it, drag it, whatever, and the check to see whether you can play an attack spell will popup and you may complete the check. Defeating it should remove the lock symbols.
 
In other words, in these encounters the spells all show up as locked until you attempt to play them - the lock is more of a warning that you'll have to do a check, rather than a prevention. This was likely to prevent player frustration from either having to make checks that weren't relevant ("I was going to use a weapon anyway!") or making misplays ("Ah shoot I forgot I'd have to make an extra check. If I'd have known that I would have checked to see if the rest of the party had a blessing to help me first!").
 
If it doesn't let you play a 'locked' spell through any means (drag, click, zoom-and-click), then it's certainly a bug.