SOLVED: My Woo Display settings got turned off by a plugin conflict.
Hopefully, this helps someone so I will post my fix. Woo Stickers now shows up on my Site Origin theme Woo Commerce shop page. I had 2 Woo “sold out” plugins active at the same time which apparently dismantled my product listing page full of images. I went back in to the Woo Commerce settings and checked thumbnail and other display options – my pics displayed again.
To resolve the plugin conflict I uninstalled both then reinstalled and activated Woo Stickers – the Sold banner worked on my “out of stock” product perfectly.
Ok, I managed to get the buttons to show up but the resulting page went from (12) 3×3″ images on my shop page to a text list with the “sold” button hanging the title of my product. I quickly deactivated the plugin but page has not returned.
Careful or you break site! Will be working on a fix for this problem now.