Thanks @mnvwvnm - tried adding your suggestion to the frontmatter and it hasn’t changed. I tried some of the other ‘Helper Class’ tags like embed-strict and they don’t appear to change anything either. Are these tags defined somewhere that I’m missing?
I’m using the old “legacy editor” (without live preview)… so I don’t know if there’s any issue with the new codemirror… but I don’t think so.
You need to check other eventual local conflicts: css snippets, plugins, etc.
It’s not the live preview but could be another conflict. I just tried it in a ‘fresh’ vault and it works so maybe it’s a conflict with another plug in. I’ll play around with that a bit. Thanks for your help!