AJAX editing leads to empty date fields on aftersave event

[Guido1982]

I have implemented an aftersave event on SalesOrders. When a salesorder is saved, the related assets are updated to change some values depending on the SalesOrder. Here is the code that does that:

PHP Code:

            if ($soData['sostatus'] == 'Niet geleverd' || $soData['sostatus'] == 'Ingepland') {
                $r = $adb->pquery("SELECT * FROM vtiger_crmentityrel WHERE crmid = ? AND relmodule = ?", array($soId, 'Assets'));
                if ($adb->num_rows($r) > 0) {
                    while ($row = $adb->fetch_array($r)) {
                         // Update the asset "keurstatus"
                        $ass = new Assets();
                        $ass->retrieve_entity_info($row['relcrmid'], 'Assets');
                        $ass->id = $row['relcrmid'];
                        $ass->mode = 'edit';
                        $ass->column_fields['cf_966'] = $new_asset_status; // Adjust custom field ID
                        $handler = vtws_getModuleHandlerFromName('Assets', $current_user);
                        $meta = $handler->getMeta();
                        $ass->column_fields = DataTransform::sanitizeRetrieveEntityInfo($ass->column_fields, $meta);
                        $ass->save('Assets');
                    }
                }
            } 


The weird thing is, when I perform the action by doing a full edit on the SalesOrder, it works as expected. But when I do an inline edit on the SalesOrder, all the date fields in the asset (custom and regular) get set to '0000-00-00'. This happens after the last line of code (I output the column fields to a temp file and tested that in various places in the proces). I've never experienced this before. Do I need to set some $_REQUEST value maybe?