I'm having this exact same issue. The site I ordered from uses the Shop app but the seller also provides a tracking number for Canpar that I pasted in the Deliveries app but there are no updates coming in yet two have appeared on the Canpar website and the Shop app. This app has worked flawlessly for me with Amazon (actually better than Amazon's own tracking), USPS, Canada Post and other couriers.
I wasn't sure if I should post a separate question. I couldn't upvote this one.