From your description, it sounds like this would have Slack's problem (which resulted in one of the most upvoted HN threads of all time, https://news.ycombinator.com/item?id=21589647). I've tried Googling around a bit to find an example of Jira Cloud's Markdown environment, but couldn't find one. (I am certainly biased, though, by my strong loathing of Jira.)

The new bitbucket markdown editor works fine actually, so I’d hope they used that.

FWIW, I prefer Jira's editor to Slack's.

Yeah, and in the end, you can export it as a word or PDF document.

Holy hell, what a tragedy. I used to write markdown and have pandoc typeset a pdf in the company design. Now I have word.