In general, don't overuse formatting. If you can make do with a paragraph containing one italicized word and a "short" quote, don't turn it into a bulleted list with bold and italics and superscript ...
As you can see at Meta Stack Exchange there have been quite a few reported bugs with table preview, Known issues: if the table contains any tab characters it will render incorrectly. There must be a ...
^That's a table at the top of the edit window^
This is a table with no blank line of text before it:
| A header | Another header |
| -------- | ---------...