Fanbox not showing

Sveltoss,
That's not something we had seen before, but clicking on the group links you posted above has this message at the top:

This group is scheduled to be archived
Over the next few months, Facebook will be archiving all groups created using the old groups format. When this group is archived, its wall posts, photos and discussion threads will move to the new groups format, but group members will need to be re-added.

My guess is that Facebook has simply disabled groups from using the Fanbox functionality, and if so, there's not much we can do about it.

In their "Learn More" section about the update, they note:

Keep in mind that the new groups format was designed to help you share with the small groups of people in your life. If you’ve been using your old group to promote your business, we recommend you create a Page instead. Learn more about the differences between groups and Pages.

This move on their part is likely a way to push people toward using Pages instead of Groups.

Hope this helps explain.. not a perfect solution, as I'm sure you don't want to move to a Page and loose your group followers, but honestly, I think that's the only option.

Yeah, I didn't like having to get that answer to you, in all honesty. Hopefully it works out well. Pages are definitely what Facebook is pushing a lot of different areas towards, so I think it'll be best in the long run.

Good luck and best wishes to you and your site(s)!