Can't get walk.qml to display element.tick

Please help,
I'm a newby when it comes to writing plugins but keen to learn. I used the createscore plugin to generate a score then I ran the walk plugin on the created score to view all the notes and rests. I used the walk.qml file that was shipped with musescore. In all cases (notes and rests) the element.tick value is reported as undefined. Does this need to be initialised somehow? Musescore version is 3.6 on Win10 64 bit.