@jazzr
I have been experiencing this issue since the middle of July. I have reported it to customer service a few times, however, the issue persists when I use the share hyperlink on listing pages or the drop-down list on my Manage Active Listings page. I can share listings on Facebook using the Social page here:
https://www.ebay.com/sh/social
You can check out my post on the Technical Issues Community Board here:
https://community.ebay.com/t5/Report-eBay-Technical-Issues/Sharing-Listing-to-Facebook-Error/td-p/33...