I had it yesterday, went into this [ancient or ancestors] glade for the moths and then couldn't leave without crash to desktop (CTD).

followers at the time:

Vilja, Serana(quest), Lydia, a thrall hunter and my SPERG-dog (yes I know, I am more of a touring guide for my followers than a hero adventurer).

I could enter, do whatever I want inside and finish the quest, as soon as I tried to leave the cave CTD.

After a few more attempts, I started sending followers their way.

Hunter gone, Serana sent home, Lydia asked to follow Vilja, Vilja to lead the way (so she would leave the cave before me) and sent the dog selling stuff.

Without followers, I could exit the cave and just play on.