Inserting "bad" custom HTML snippets (incomplete, missing quotation marks/ closing brackets and that sort of thing) completely messes up editing posts you always get messages about no text body existing. You have to strip any custom formatting via HTML editing and then start over to even fix a simple typo. More to the point, the editor seems to just dumbly repeat HTML tags to retain its paragraph structure and in doing so produces invalidly nested HTML, which then of course will be rejected by the syntax checker/ sanitizer.
Mylenium
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