Thank you for the link, much appreciated!
I have tried several things to make the plugin work, and finally I managed, but I have no idea what the problem was. Right now I am back to all my old settings and the plugin still works.
The only thing is, on the dashboard, when I’m writing or editing a post or page in visual mode it still gives the message that no items are found. But after publishing it shows the gallery like it should. Is this normal?
Other than that, great plugin!