In another thread, The_Red_Queen pointed out that in this patch enemies seem really unobservant of arrows and bolts hitting them from unseen sources, which I've experienced as well. [edit: and in this thread while I was writing this, lol]
Yes, I have banged on about this Sorry for the repetition.
"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"