Update / delete / refresh WordPress Thumb Cache

Hi
I recently updated the featured images on some WooCommerce Products (by deleting the old ones, and uploading new ones with the same name and then adding them again in Featured Image) but no matter what I do, I can’t get the site to show the new images.

On the product page, the new image is showing in the Featured Image section, but at the front end I can see that the browser is getting the image from the wp-content/uploads/thumb-cache/ folder and it’s showing the old image.

I have tried two plugins – Regenerate Thumbnails and Ajax Thumbnail Rebuild, but neither of those seem to have done anything.

I get the feeling I’m missing something. I don’t think this is a browser cache issue, as I’ve emptied the cache and viewed the site on other browsers and they all show the old images.

So how do I force WordPress to regenerate those thumbs? Or is it perhaps something specific to WooCommmerce? Any help much appreciated.

The site is not live yet so I can’t show a link, but there’s nothing really to see anyway.

Geoff