This can be solved by editing the file "common/toolbox.php" and replacing . . .
line 386 ($filter = "(e.type = {$typ} AND c.`noverlap` = 2)";) by

$filter = "(c.`noverlap` = 2)";

and line 388 ($filter = "(e.type = {$typ}".($eid ? " AND e.`ID` != {$eid}" : '')." AND ((c.`noverlap` = 1 AND c.`ID` = $cid) OR c.`noverlap` = 2))"; //if update, exclude event self) by

$filter = "((c.`noverlap` = 1 AND c.`ID` = $cid) OR c.`noverlap` = 2)".($eid ? " AND e.`ID` != {$eid}" : ''); //if update, exclude event self

and line 414 (retrieve($sDate,$eDate,'',$filter);) by

retrieve($sDate,$eDate,'',$filter,$typ);

Use cut & paste !

You can also send us an email via the Contact Us page and we will send you the updated toolbox.php file.
Roel