Report the Feed.php bug to Realmac. Item links come from $item->url() (relative) when Item::canonicalUrl() sits right beside it and returns absolute. Your app is now immune, but generic feed readers — Feedly, NetNewsWire, anything aggregating your Studio Notes — will still mishandle relative <link>/<guid>, which RSS 2.0 doesn’t allow. Good beta feedback while 3.0.6 is still in flight.