Random Group Bug
 

I don't know if this is me or not... but at random intervals I get grouped bug, for 1 mob. I can't send my pet to attack and my spells don't do any damage. As well as the mob's health not updating.

I'm not lagging, as the spells appear to cast and chat goes through normally... then on the next mob it'll work fine. Never happens while soloing.

I've had this happen quite a lot recently. For me, if I clear my target and re-target, it seems to fix it.

there are some target de-sync issues.. if anyone knows exact steps to replicate it please post or pm it to me.

I am not sure about the health bar updating, but the not-being-able-to-attack definitely happens if you /assist before the mob is in sight/range.

ah ha de-targeting/re-targeting does seem to fix it :)