This is really specific, but if a field uses the rendered view formatter for nodereference, the fieldgroup will still display even if the field is empty. I suggest changing line 1008 in field_group.module from

elseif (!empty($element[$name])) {

to 

elseif (!empty($element[$name]['#items'])) {

which will fix the issue.

Thanks

Comments

nils.destoop’s picture

nils.destoop CreditAttribution: nils.destoop commented
Status: Active » Closed (works as designed)

Seems like this is already fixed with latest version of nodereference.