Larian Studios Forums Baldur's Gate III Baldur's Gate III - Help Tips & Tricks Thaniel? (Act 2 Quest)

I spoke with Halsin and met him at the lake to protect his portal until he brought back Thaniel.
He then joined my party (after talking at camp) and we set off to find Oliver.
We won the two rounds of hide and seek and Oliver vanishes through a portal.
On going through the portal, you are immediately in a battle and have to destroy shadow creatures to make oliver's protective globe vanish.
I brought down the globe and immediately entered a cinematic - I persuaded Oliver to join again with Thaniel and he 'dissolved'.
Halsin congratulated me and informed me the shadows would start to disappear.
The cinematic ended and my whole party died immediately of 'shadow damage' - Unable to port to Camp or heal

Quite disheartened of this outcome as the only saves are back before entering the portal - Tried again and had the same thing.
Saw a post on steam where the same thing has happened up to 10 times.