During the Rose of Remembrance quest if you go with Triss and don't have a bath with her you get stuck in the bath area. The only wall that can be broken with the Aard is the one that leads to the area where you fight Letho. The exit never has a wall blocking it but you can't climb out.

There is no problem with having sex with Triss and waiting for Roach to find you. After talking with Roach you can climb out.

At present this makes it impossible to get the ability Resistance to Magic.

It worked for me a few days ago. You sure you're trying everywhere? I got out but didn't talk to Triss before opening an exit if that affected it.

After dropping through, I immediately used Aard on the wall and it worked. She then forced a conversation with me in which I chose to leave.

Hm. Got stuck in the same place. The problem is that I've had already demolished the wall before Geralt and Triss fall through the ceiling and now I am not able to use Aard in there before they start to talk - when I hit Q (for Aard), I am immediately shown another conversation... I guess I won't have the resistance to magic...

So I guess the advice is: don't touch the wall in the ruins before you fall in there with Triss...