Hi!
On the page "admin/content/node-type/xyz/display" I can choose how to display a fieldgroup. The Option to display as "fieldgroup" displays the group as a collapsible group. Just the same as if I chose "collapsible fieldgroup" or "collapsed fieldgroup". Why is there no difference?
I thought this could be browser-related, but it is the same in ff, ie and chrome.
And, oh, I am using a custom template with "print $group_xyz_rendered;" but the problem persists even with the standard template.