Hysteria (or lunacy) I forgot what it's actually called seems bugged. I've tanked the bone dragon 20 something times now and more than half the time I will get hit by the Hysteria debuff and I'll just stand in place stunned for the duration of the effect rather than walk around. Only once did my character actually move around with hysteria on.

One thing I do though is keep my back against the arena wall and I kind of recall being higher up the one time hysteria made me actually run around, so maybe being close to the zone boundary screws with the effects path-finding calculations.