Captive won't exit cage, she also can be walked through, like a noclip cheat.

[Tillile]

I'm in Trachis Fort and The only thing left to do is free the last captive but she won't move. It's like only the image of the NPC is there but the AI is turned off and she can't be touched, you pass right through her.

[UbiBaron]

Thank you for reporting this to us.

The first thing we'd advise is trying to fast travel away and then head back to the Fort.

It may also be worth waiting and turning it to night/day.

- Ubisoft Support