How to make visual studiio code allow special characters(%) as emmet?

I have added the following snippet to my jina-html.json file

"open block": {"prefix": "%%","body": ["{% $1 %}$2"]},

When I hit tab it does nothing except a regular tab

When I change the prefix to a letter character it works and any other special character does not work either. Is there a way to make it work with special characters?