Not the OP but this is happening to my site as well. Tried everything they posted about, no dice. I am using a custom theme, but switching to different ones isn’t alleviating the issue. Talking about custom emojis used in posts like this:
It’s not the biggest issue in the world because you can just post the image itself to get around it instead of :emoji:. Still weird though, and if there’s a solve I’d love to know.