In the coding for the store module, the Author ID field is mistakenly named 'ResponsibleID'. This piece of code seems to have been copied from the Events module which is the only module in Dolphin with the Author ID field called 'ResponsibleID'. See fix below :
In modules\boonex\store\classes\BxStoreModule.php :
Inside the isAllowedCreatorCommentsDeleteAndEdit function, find :
if (!$GLOBALS['logged']['member'] || $aEvent['ResponsibleID'] != $this->_iProfileId)
Replace with :
if (!$GLOBALS['logged']['member'] || $aEvent['author_id'] != $this->_iProfileId)