I apologize for any inconvenience, our team is aware and working on solving the issues with not being able to upload images using internet explorer and Microsoft edge. As of now, we would recommend using google chrome to edit the website until we get this fully resolved. Are you using google chrome or Firefox when editing?
I do apologize for any inconvenience this has caused. I was able to successfully upload images to the WebsiteBuilder sites on the account. Were you still experiencing this issue? You can also try using Firefox.