For further info on this patch see Security Patch SUPEE-8788 - Possible Problems?
Check that you have no custom admin theme files overwriting the patched files for SUPEE-8788. The admin files affected are as follows:
app/design/adminhtml/default/default/template/catalog/product/edit/options/type/file.phtml
app/design/adminhtml/default/default/template/customer/tab/view.phtmlapp/design/adminhtml/default/default/template/login.phtml
app/design/adminhtml/default/default/template/notification/toolbar.phtml
app/design/adminhtml/default/default/template/oauth/authorize/form/login-simple.phtml
app/design/adminhtml/default/default/template/oauth/authorize/form/login.phtml
app/design/adminhtml/default/default/template/resetforgottenpassword.phtml
app/design/adminhtml/default/default/template/sales/order/view/history.phtml
app/design/adminhtml/default/default/template/sales/order/view/info.phtml
There are some minor changes in these files that need to be applied to your custom template files in order for MageReport to confirm the patch is in place.