Hannag encounter (bug?)

[Teal V2]

Situation is the following.

I found Hannag, who was doing her stuff, barricading herself against the magisters.
I talked to the magister about I will kill Hannag for them.
Then I talked with Hannag, "I don't want to hurt you", then she fled to a higher level into the ruins, barricading herself again.
We went after her with the magisters. They stopped in front of the barricade.
I went in to talk with Hannag.
I convinced her about that I want to help her, then she sent me to kill the magisters.
I started a fight with the magisters. Hannag was doing her endless magic casts in the background as usual.
During the fight, an archer used Tactical Retrait and jumped inside Hannag's cast area.
Hannag joined into the fight as an enemy without saying a word.
She then started her animation where gets restrained by chains and portals are summoned.

Is it supposed to work like this?
I mean.. I was with Hannag, this is how we agreed.
An archer getting into her "animated magic cast zone" should not make her hostile?