Not sure if this has been fixed before or even reported but I've seen various reports for one of Pineconn's quest's that depend on this behavior saying that it doesn't work in newer beta's.
2.10 reflecting fireballs injures Darknuts.
Dunno. It's definitely working for me.
The quest in question was designed for 2.10 (I believe it is Link to the Heavens).
I tried it in End of TIme DX. Come to think of it, though, Darknut defenses were one of the things I fixed in build 1258, and there hasn't been a Windows build since then.
* Fixed enemies in old quests. That doesn't necessarily mean they all behave corectly, but they should all act the same in both old and new quests now. ( Saffith, 2010-05-15 13:17:17 )?
It would have been better if you listed what was affected then just using a vague description.