Ascent to Power bugged at "Search Traitor's Passage"

<blockquote class="imgur-embed-pub" lang="en" data-id="a/RSQWEn0" ><a href="//imgur.com/a/RSQWEn0">poe2 bug report</a></blockquote><script async src="//s.imgur.com/min/embed.js" charset="utf-8"></script>
This bug was caused when my friend in co-op picked up the quest reward. Now no matter how many times I kill the boss in the traitors passage, I cannot progress to unlock my ascendancy. This could be fixed if I could just reset the questline somehow