Sorry for the necro, but since this bug is still not fixed i thought i'd post a workaround.
This crash usually only happens if you enter sorrowflow a party, and can be prevented by entering alone.
It takes 3+ days to send your party away if you are already there, so you may want to take the trip from the capital alone.

I appreciate the necro because I just purchased the game and this information is helpful. Question: Is this bug experienced by all players or only a select number?

I entered this map just yesterday. I have the last version of the game and i entered sorrowflow with full party.
The screen behaved oddly (all black for various seconds) but ultimately tha camera shifted to the cliff where there are the tieflings. After the dialogue I had the options to send my teammates back to the city to continue the mission. I didn't have particular problems.
When i finished the mission i went out of the area and came back and my previous party reappeared.

Went there yesterday as well (first time playing), and didn't have any issues. The party got sent back, and the tiefling added to the "group". A cutscene showing the tower and then I got control again, without any noticeable delay. After leaving the area we got a random encounter, which I thought would be hard with only two people. But then the normal party was back together.

Didn't pay attention if 3 days disappeared, though.

One annoyance I've noticed, however, is that buffs such as Bless will disappear when doing environment Athletics checks and the like, even if I just buffed up. Don't think it happens every time, but definitely sometimes.