The side quest A Sodden Pact in Scosglen cannot be completed for many players due to a bug. Here is an easy workaround to be able to complete the quest!
A Sodden Pact Side Quest Guide A Sodden Pact Side Quest Bug Thread – Diablo IV Forums
A Sodden Pact starts immediately after completing the Whispers from Below side quest. After speaking with Roina, you are tasked with collecting hair from the Sodden Growths. At this point, Roina will start following you.