In QtQuick whenever you change data within a QAbstractListModel, you have to notify Qt in some way. It’s not as straightforwardly reactive as in modern web-frameworks. When adding, moving or removing items from the list, the operation needs to be enclosed by beginInsertRows/beginRemoveRows/etc and endInsertRows/endRemoveRows/etc.

Changing data inside the list-items needs to be followed by an emit of dataChanged, which takes the item-position in the list as argument.