@carlw I did a reimplementation of TodoItemFragment without looking at the old code. That worked perfectly. I think I must stop looking for a bug in the framework and rather identify the difference between the original version and my reimplementation. I first did an ultra small implementation with a builder and then changed to FXML when I couldn't reproduce the error anymore, and it's still good with the FXML version. Will keep digging and let you know what I find 🙂