Pandaria Can't attack the Cow King

[Remphan]

Like the title says I can't attack the Cow King with anything (even aoe) > "Invalid Target"
Tried to enter the circle - nothing, died - nothing, re-enter the instance - nothing.
Any suggestions what to do?

ps King attack me
this problem occurs on both characters i solo cleared instance with (warrior and warlock if matters)
both are on different raid IDs