Meteor + vue guide demo problem

I’m having trouble getting the Meteor + Vue guide demo at
https://github.com/meteor-vue/guide to work. The button text changes as expected when clicked, but the reactiveVar that shows the number of clicks always displays as 0. In the debugger I can see that the value of counter is being updated, but the computed function count() is never being called.

On the Blaze page, the time is updating in the Blaze template section, but not in the Blaze block helper section. Changing the Data context and Reactive slot value doesn’t do anything (should it?).

I’m using an unmodified clone copy of the demo directly from GitHub with Meteor 1.6.0.1 (the latest patched version) via the latest Firefox and Chrome browsers. Is this an issue with the demo or my install of Meteor (I had a lot of trouble upgrading from 1.5) or something else?

UPDATE
Moving the ReactiveVar counter to data and making the associated changes fixes the problem. Either ReactiveVar or computed: seems to be broken.