One possibility to look into:
If the problem only occurs when using Firefox, try temporarily disabling Enhanced Tracking Protection on ebay.ca, bulksell.ebay.ca, rover.ebay.com and ebaystatic.com by going to each site and clicking on the shield icon to the left of the page address in the browser address bar.

Try copying these links and pasting them into your browser address bar for the other sites:


https://ir.ebaystatic.com/pictures/aw/pics/s_1x2.gif
https://bulksell.ebay.ca/ws/eBayISAPI.dll?SingleList&forcetool=CUB
https://rover.ebay.com/robots.txt