Update: our website https://www.ixstudios.nl/ now does show up on mobile devices, connected to a F-Secure secured network. Strangely enough, desktop browsers still get blocked.
As far as i can tell, with search-beta and chatra, the site gets presented correctly now, although be it only on mobile devices. It should be safe, and hopefully this is just a strange exception from F-Secure.
Will keep updating this post about F-Secure if there is news.
Update: This has been resolved - more than a week ago! Sorry for the late update.
So if your sites gets blocked, go to the f-secure website and request/send a fix/problem and hopefully your sites works again after a couple of days.