Can't leave bugged boss arena

Hey,

I completly stuck in the middle of fight with map boss.

Boss just disappeared, so I can kill him, I cant die.. I can not respawn to nearest checkpoint - since I do not have that button available - tt

I tried with friend, I can not tp to anyone and neither any1 can tp to me.. After game reboot or relog I'm comming back to bugged fight arena, so my game is over.

Please help

BR,
Peter