LaTeX not rendering when downloading note as html

### Is this a hackmd.io issue?

Yes, the bug happens on https://hackmd.io

### What's the problem

LaTeX is not rendering when downloading as `html`

### Current behaviour

I've tried in Firefox, Chrome, and Edge (both downloading from and viewing in). Here is a screenshot of one of my notes:


### Steps to reproduce:

Write some LaTeX, try to download your note as `html`.