Spells: Can't cast on target when both caster and target underwater

[kaev]

Server: green
Zone: Oasis
Croc flees, pathing takes it underwater, can follow and hit it with melee (both player char and mob underwater) but spells interrupt at end of cast time with "You can't see your target from here." message, despite the fact that both caster and target are underwater and in melee range.