It seems that as of meta-box-groups version 1.2.12 the plugin slug was changed from tmeta-box-group to meta-box-group. This hads serious implications when using code like so:
if ( is_plugin_active( 'tmeta-box-group/meta-box-group.php' ) ){
include ('inc/config-meta-boxes.php');
}
Where in the hell was this major change announced?