@Coffeebreak - Thanks for the update regarding having to camp in the wilderness. It's not clear that the Go to Camp and End Day button when pressed in the wilderness is a Long Rest.

However, this isn't resolving the bug which I have found. Circumstances of my run:
- Until the point of freeing Halsin, I have had no long rests (I was attempting a "No-Long-Rest" run. No return to Camp and therefore none of the other Long Rest Cut Scenes have occurred.

- I arrived back at the Grove not expecting to bump into Halsin (I was just going back to sell my goods and buy more fruit/healing potions), but his cutscene triggered. Just like the OP I was required to take a long rest (hard requirement it seems).
- Went outside of the Grove, clicked the "Return to Camp and end the Day" button. I'm still teleported back to the camp. I then get "The Deal" cut scene (not the "Celebration" cut scene)
- Tried to go further into the "wilderness", clicked the "Return to Camp and end the Day" button. I'm still teleported back to the camp. I then get "Shadowheart Strange Magic" cut scene (not the "Celebration" cut scene).
- Tried to go even further into the "wilderness", clicked the "Return to Camp and end the Day" button. I'm still teleported back to the camp. No "Celebration" cut scene...
The Celebration cut scene never triggers and am stuck.