As I indicated (and as many eBay users can attest), IE is not the best browser to use for eBay. Some functionality may be lost if you're accessing eBay on Internet Explorer, and in general, IE just doesn't work well with eBay (which is full of glitches).

Canon's Easy-WebPrint may be just one of several functionalities that simply don't work on eBay. The eBay technicians love to "tinker", but only at the behest of eBay's instructions (that is, not for the average eBayer's convenience). You can try getting in touch with eBay Customer Service, but I doubt you'll get any real help. However, here are the contact details if you want to try that. eBay's "Have us call you" option is by far the best way to get in touch with eBay. (Emails are useless, for a number of reasons, but primarily because the responses, when they are finally sent, are bot-generated.)

eBay say: We'll call you at the phone number registered to your account, or you can enter a different number.

We’re available from 8am to 10pm AET, 7 days a week

My suggestion would be that you use a different web browser - such as Firefox or Google Chrome. I use a variety of browsers, as some websites are rendered in a better fashion on one browser than on another.

Canon's Easy-WebPrint is only available as an IE add-on, so you'd need to look at an alternative add-on for Firefox, for instance. Here's the link for add-ons using the search terms web and print. https://addons.mozilla.org/en-US/firefox/search/?q=web%20print&platform=WINNT&appver=60.0.1.