it it then then highly likely to occur on the boss.
The bug is as follows the first turn , you will stay in the "positioning phrase" even though its your turn. To fix this this, you need to log out and log back in OR go back to character selection, upon re-logging you will be able to use all your spells however you just wasted 15 seconds plus. Also chances are the rest of the party will be bugged are high on their first turn so they will need to relog their first turn as well. If an osamoda uses a summon first turn they will need to re-log twice. Once to summon then again to fully control the summon.
Also if someone is bugged and they are unaware they fight will lag i.e not progress, sometimes the playing who is bugged may re-log but it already skipped their go.
Ticket number #1417993 contains my wakfu log and zip folder of the game account.