Hi Frederica,
We've got a Moodle 3 upgrade coming up in the summer so it's definitely something I'll be looking into soon! I can't see your attached screenshot but my guess is that version3 has renamed some of the DOM elements, specifically the completion tick boxes.
In my code the script is looking for these tick boxes as 'input[name=completionstate]' (input elements with the name 'completionstate') This might have changed in 3.0. You could try uncommenting the console.log debug messages in the code to see what's being picked up, i.e. if any of your completion tick boxes are being counted. If not, then the dial won't animate as it will remain at zero.
I can't off-hand see any real reason why the code for the css animation itself would stop working, but I'd have to try it out on an actual installation.
Hope that helps a little. I'll let you know more once I get my hands on our own testing server