Since it works in the beta (non-sandboxed) and not in the App Store
version, I suspect it's related to problems with sandboxing, and Apple
At this point, you have two options:
1) Download the MathJax script to your local computer in order to access
it that way.
2) Use the v3 beta. With the exception of really long documents (due to
extra testing that is performed until the beta is complete), the beta is
better than v2 in just about every way.
I'll look to see whether this any way around the App Store limitations
in this (it used to work fine), but I can't promise yet. But I'll need
to figure it out before v3 goes into the App Store anyways...
Thank you for your solutions! For the v3 beta and other non-sandboxed ones, I just cannot open it in my mac. (macOS Sierra v10.12.4), the only composer I can open up is what I downloaded from apple store...
So now I am more curious about the first option. I have already download MathJax to my computer. But I am not sure what I should do next. It seems that I need to link the Composer to MathJax in some ways, but I don't know how to do it. Looking forward to your reply!