If you have blank lines in your YAML frontmatter such as below…
---
title: My Title
slug: /slug/
---
In Notepad++ —
- Replace Tab
i). Ctrl+H
ii). Find what:---(?:(?!---).)+?\K(\R){2,}(?=.*?---)
iii). Replace with:$1
iv). CHECKWrap around
v). CHECKRegular expression
vi). CHECK. matches newline
vii). Replace all
or
- Find in files
i). Ctrl+H
ii). Find what:---(?:(?!---).)+?\K(\R){2,}(?=.*?---)
iii). Replace with:$1
iv). Directory (input or navigate to where the files are)
v). CHECKRegular expression
vi). CHECK. matches newline
vii). Replace all
You might need to repeat either process if there are more blank gaps.