I couldn’t wait and just created a quick (and dirty) workarround:
I replaced the following lines in the group-to-wp.php
$access_token = $option['app_id'] . '|' . $option['app_secret'];
with
$access_token = "xxxx";
Take the access token from https://developers.facebook.com/tools/explorer/
and
$fb_url = 'https://graph.facebook.com/' . $group_id . '/feed/?limit=' . $limit . '&access_token=' . $access_token;
with
$fb_url = 'https://graph.facebook.com/v2.0/' . $group_id . '/feed/?limit=' . $limit . '&access_token=' . $access_token;
Works fine for me, also with the “pagination”… ??
*edit*
Sometimes (every 20 Sites maybe) I got the following error:
Warning: First parameter must either be an object or the name of an existing class in /var/www/xxxx/html/xxxxxxx.xxx/wp-content/plugins/fb-group-to-wp/group-to-wp.php on line 313
But after hitting F5 / reload the page, everthing works again. ??