Session doen't get data

Hey, no I haven’t found a solution yet.
The problem is, that you can’t set a new session Item, after opening the lightbox:

This works:

session.setItem("key", "I am a String");
wixWindow.openLightbox("Formular");

This doesn’t work:

wixWindow.openLightbox("Formular");
session.setItem("key", "I am a String");

You can try it with a container instead of a lightbox.