Hi.
You were right to switch to internet explorer. It is the new browser called The Edge, that Windows 10 launched this summer. You were probably using the Windows 10 Edge Browser, which is conflicting with Canada Post shipping labels, through Paypal and may be affecting your login as well for eBay. Whenever you are doing anything eBay related, and shipping labels, make sure you are using browsers such as Internet Explorer or Firefox. There may be others as well that are compatible.
Hope this clears it up for you.