I'm not sure if this is a patch bug, a general bug or just how it's meant to go, but looks like it's impossible to even have a proper conversation with Mirke if you only talk to her after you've resolved the Benweth quest, let alone recruit her.

Hey Osra,

 

Do you happen to have a save game where this issue is occurring? We have had some issue with recruiting Mirke in the past and may have missed this instance.

 

Thank you!

 

-Caleb

Unfortunately, it got overwritten before I had a chance to make a separate save. But the next time I tried I talked to her first and then went back to her after I dealt with Benweth and it worked fine.