BBCode tags such as [b] don’t work if the content inside includes line breaks.
(Yes, I know that in markdown you’re supposed to keep it all on one line, but in bbcode everything inside a [b] tag should be bold regardless of content)
Example:
[i]one line test[/i]
[i]consecutive lines test
line 2[/i]
[i]consecutive paragraphs test
paragraph 2[/i]
one line test
consecutive lines test
line 2
[i]consecutive paragraphs test
paragraph 2[/i]