Hello,
Your problem is related to images that you used for your products.
The minimum image size should be 200 x 200 pixels. At the same time, your image must not be larger than 8MB.
I checked your products and see that you use too small images http://prntscr.com/hgccc2
Once I uploaded correct image then it works fine for FB, see example https://angelspath.eu/product/σκουλαρίκια-αιματίτη-τριαντάφυλλο/
Regards