fieldgroup.tpl.php unable to override

Same for me, or maybe we do something wrong?

Same problem here.

Make sure you have selected 'simple' display in admin/content/node-type/{your node type}/display
Then copying the template file should work. But it doesn't.

I think the problem is to do with naming conventions in the theme function, fieldgroup_theme():

Around line 60 in fieldgroup.module, this doesn't seem to allow for template recognition:

    'fieldgroup_simple' => array(
      'template' => 'fieldgroup',
      'arguments' => array('element' => NULL),
    )

But this altered code works when using a template called fieldgroup_simple.tpl.php

    'fieldgroup_simple' => array(
      'template' => 'fieldgroup_simple',
      'arguments' => array('element' => NULL),
    )

+1 same problem here

Confimed.

-asb

Same problem.
@subscribing

+1. Subscribe.

Cheers, Dave

Same problem here

Confirmed that the fix in #2 works. Not sure though if this is a CCK or a core bug?

Fixed in latest -dev. Thanks fiskit for the catch.

The template is now named fieldgroup-simple.tpl.php, and allows template variants :
fieldgroup-simple.tpl.php
fieldgroup-simple-.tpl.php
fieldgroup-simple-.tpl.php
fieldgroup-simple--.tpl.php

I just approached Drupal, but I'm pretty sure I followed the correct steps for creating a custom override of a group named "caratteristiche". I placed under sites\all\themes\mythemename\ a copy of \sites\all\modules\cck\modules\fieldgroup\fieldgroup-simple.tpl.php and customized it to my needs.
The weird thing is that keeping the filename as fieldgroup-simple.tpl.php (after flushing the theme cache) keeps the customizations, but trying to rename the file to override a more specific item like fieldgroup-simple-group_caratteristiche.tpl.php doesn't work.
I also installed the devel and devel_themer modules and I found out that the override name was correct, so I searched through the bug reports and found this, and thought it might be related.

EDIT: I put the theme name in the shape of a tag, and it was gone missing

I had some time to test another couple of options and I just found out that placing just fieldgroup-simple-group_caratteristiche.tpl.php is not enough - I had to include ALSO fieldgroup-simple.tpl.php, even if it's not customized. That way the content-type specific customized file is correctly applied.