A cutscewne should ahv played then entering right?
You need to defeat the enemies after that another cutscene should play.
It's a glitch, I definitely fixed something like that it in the past, just can't remember which version it was. Which version are you playing?
Also it should not be game breaking, after defeating 8 enemies the quest should still progress, so it shouldn't be a softlock.
Feel free to keep me update if you think you are stuck.
I also always could take a look at your save, in the worst case!