Mathjax doesn't render correctly on github.io, but works locally?

Hi eveyone.
I have a problem with my Latex formula. Here is my code

$rank(\textbf{A}) = dim(span(a_{1*}, a_{2*}...a_{m*}))$

It works well locally. But on my github page, it doesn’t render correctly. Screenshot from 2021-08-24 10-06-53

I realized that it my script have a pair _{ _{, and it can break my Latex formula. Could you help to fix that?