Yes, that's because the (?!\s*###+) only needs to match once, at the end of a line. You need to modify the regex to have match at start of every line.
In reply to Re^3: Regex assistance, please.
by moritz
in thread Regex assistance, please.
by clueless newbie
| For: | Use: | ||
| & | & | ||
| < | < | ||
| > | > | ||
| [ | [ | ||
| ] | ] |