I'm seeing a difference depending on browser. In Firefox and Safari both the hyperlink and image buttons seem to work correctly (a popup appears where I can enter the website/image URL). In Chrome this popup does not appear.
The editor in Chrome does seem to add the <a> and <img> tags to the HTML, but it does not give the user the chance to enter the href or src values.
Screenshot of the hyperlink button working correctly is below:
Here is what support said:
Looking into this, I do see that this is a known situation, and I will attach your case to our tracker about this so when we have any new information you will be updated. It does look like the Insert Link and Image buttons do work in Firefox and Safari 12 currently, and that workaround should allow you to add links and images. I do apologize for the inconvenience this has caused.