Why do code blocks sometimes not “show” properly?
Code markdown seems to break down for this answer:
The markdown itself looks OK:
Did something change recently in the markdown display mechanism?
Not sure what wonderful characters were used instead of a space on those three lines, but re-indenting the lines fixed the issue.
When deleting the whitespace characters one-by-one, the preview display showed that every second 'space' did not affect the display; perhaps it was a non-breaking space instead of a regular space.
In other words, not a markdown bug, but rather a case of unsupported input.