`$$ $$` doesn't work in MathJax 3 or KaTeX

I find putting backticks around block-displayed LaTeX code doesn't render using either MathJax 3 or KaTeX, for example

$$\Gamma$$ \[\Gamma\]

However rather than backticks you can just enclose the LaTeX code in a div. This works fine provided the div begins within 3 spaces of a newline, that only spaces follow the end of the div, and that the line following the div is blank.

Previously I used MathJax 2.X and then the backticks worked