wgteams/class/members.php Zeile 140:

$uidSelect = new XoopsFormSelect(_AM_WGTEAMS_MEMBER_UID, 'member_uid', $memberUid, 1); $uidSelect->addOption(0, ' ');        
$member_handler = xoops_getHandler('member');  
$listUsers = array();  
$listUsers = $member_handler->getUserList();      
foreach ( $listUsers as $key => $value ) {
       $uidSelect->addOption($key, $value);  
}  

ersetzen mit:

$uidSelect = new XoopsFormSelectUser(_AM_WGTEAMS_MEMBER_UID, 'member_uid', false, $memberUid, 1, false);