Water surface blocking line of sight bug

[Ciderpress]

I'm posting this here instead of in bug reports because I'm sure it's been posted there a million times.

Was this bug deemed classic and that's why it never gets fixed, or is it some limitation of the titanium client, or wtf? It's maybe the most annoying bug in the entire game, and I don't remember it always existing on p99 although maybe it did.

Mob is being killed\fear kited. Mob flees or is feared into the water. Attempting to cast on the mob now returns a red "You can't see your target from here" message, whether you are on land, in the water above surface, or in the water below surface- the game just refuses to let you land spells on it.

The most annoying part is that sometimes it *doesn't* happen, and you can still cast on the mob fine, so it's extra maddening because I can't figure out what I might be able to do on my end, if anything, to avoid it. Happens with snared mobs, unsnared mobs, whether or not I have lev on etc etc..

It's rare it doesn't happen though, because it wouldn't be so bad if it was a really rare occurrence, but I'd say a solid 85-90% of the time if a mob gets into water (and specifically if it goes deep enough that it engages their swimming animation, assuming they have one) you can no longer cast on it, and you're just stuck hoping that it randomly paths back onto land.