splice of QStringList in QML no longer working

The splice function on the QStringList and QList<QString> objects exposed to QML stops working as expected (still can find the target, but can't remove it), While plain JS string list works fine. Attached is some simple code to re-produce this, and the following is the console log output:
original stringlist: 3 (qrc:/tmp.qml:8)
splice of stringlist: bbb (qrc:/tmp.qml:12)
stringlist after splice: 3 (qrc:/tmp.qml:13)
................ (qrc:/tmp.qml:15)
original list of string: 3 (qrc:/tmp.qml:18)
splice of list of string: bbb (qrc:/tmp.qml:22)
list of string after splice: 3 (qrc:/tmp.qml:23)
................ (qrc:/tmp.qml:25)
original JS string list: 3 (qrc:/tmp.qml:28)
splice of JS string list: bbb (qrc:/tmp.qml:32)
JS string list after splice: 2 (qrc:/tmp.qml:33)