Transition property 'running' gets stuck on true

A signal adds an item to a ListView every 1000 msec. There is a Transition that runs animations either every 500 msec or every 10000 msec and I monitor the Transition property 'running'.

With the duration of 500 'running' toggles as expected, but with 10000 it gets set to true and remains so, even when I stop adding items.

This is a snippet to illustrate the salient part:

add: Transition {
onRunningChanged:

{ console.log("running changed: ", running) }

NumberAnimation

{ properties: "x"; from: trans.localVrnOrigin.x; duration: list.animationDuration }

NumberAnimation

{ properties: "y"; from: trans.localVrnOrigin.y; duration: list.animationDuration }

}
addDisplaced: Transition {
NumberAnimation

{ properties: "x,y"; duration: list.animationDuration }

}