Lundun completely completed except for the said quest. Ranvi reported at home, back to Lundun (now the key is there), talk to Maximillian again, hire a child, do it!
This is how it worked for me!
Translated by Google
I started the Berserker quest series this morning. In between did something different and wanted to continue the series. Now the entire add-on has disappeared, the quest no longer exists. Not even in an older Save !!!