Mdx editor not updating correctly / data missing in db payload

[Firgrep]

Had some strange behaviour with the mdx editor as I've been testing some other things that it doesn't update as expected. Sometimes I input some text, only to see that it doesn't feature in the db payload. The debug button is helpful to see exactly what md string is currently stored and it too was missing the text. I solved this by re-typing what was missing but we shouldn't have this kind of gap in functionality.

We should thoroughly and carefully test this before we hit production.