Maybe other pluins make your mobile menu disable. You can try to close all plugins and open it one by one to check if the menu works.
Dear Ralph Deng
Thanks for your help. I tried to close all plugins and open it, but that didn’t solve my problem.
Could you give me other suggestions ?
I have checked your site. Do you use the “JNews” theme, right? I found one error from their jnews/assets/dist/frontend.min.js . The file name hints the file should be related to menu function. I suggest you can contact the author of JNews to help solve this issue.
Great. I found your mobile menu work.