After upgrading to version 4.6.9 the editor icons have disappeared and are replaced by empty square boxes.
I went to the fancyproductdesigner.com demos and they are missing there also. Screen shot from fancyproductdesigner.com.
You can re download the zip file again and upload all files again. There was a problem with the fonts.
Thank you! I have icons now.
My demo doesn't work, i sand the screen of the problem that you have on your product's demo : all icons are missing. this problem i see only on google chrome ( Version 91.0.4472.77 ) last version, on Firefox or Safari work fine.
The problem is also in your demos