Currently, when we switch from one editor to a higher editor (say HTML to Block), the discussions are not retained. Revision history remains. I've been told that that's the product behavior. But as a user this is a big drawback that I see. I should be able to see all the past comments on an article or at least there should be some other workaround. For instance, allows us to download the past comments along with the article. It can serve as a future reference. Please consider this use-case as an enhancement feedback.