The Aspirants Challenge NPC wont move

The NPC for this quest is supposed to fight you in the oval area where he comes to you  and he is just stuck there where he spawned at. I tried abandoning and doing it again and I just spawn more of him. The duel command while on the mount doesn't work either while trying to challenge him.

Please Help.

Thanks !

I didn't find the right solution from the internet.

References:

- https://us.battle.net/forums/en/wow/topic/2075765615945613

- video animation