Oh, it seems that I missed the last two replies. I did not get a notification for them. the last one I received a notificateion for was Pankaj with "I raised the issue to development team. I will update you here once it get fixed."
OK, concerning the cache: Our test site has caching disabled at all. And it does not work there as well.
I set it to conservative caching on our production site to test it, but it diod not help either.
Any news from your devs @Ninja?