Display of Mathjax

The notes imported from external .txt files contain MathJax formulas, but they need to be edited once in the desktop version in order to display as formulas. Otherwise, the editing symbols of the formulas will be shown. Is there any way to solve this problem?Thanks a lot.

Example:

<anki-mathjax>d_1 = \frac{ln \left( \frac{S_t}{K} \right) + \left(r + \frac{\sigma^2}{2} \right)(T-t) }{\sigma \sqrt{T-t}}</anki-mathjax>

Imported File:
https://www.jianguoyun.com/p/DZLYciIQz82XCBjL8JoFIAA

<anki-mathjax> is an implementation detail of the editor, and is not intended to be used directly. The correct syntax is shown in the manual: Math & Symbols - Anki Manual