I was able to open a .mdx file in Markdown Monster, but the preview is not showing. Can I not preview .mdx files? I opened the file using Open With in File Explorer.

Interesting I hadn't looked at that.

When you open currently, what does it show as in the editor? Just plain text I assume?

I can get the syntax support hooked up at least for the markdown part of it easily enough, but the rendering is something that requires extra tooling and that wouldn't be part of MM directly. Perhaps as an addin...

+++ Rick ---

It opens like an .md file does. It seems like the syntax support is there. I just can't preview it. I'm not skilled in creating add-ons. Hopefully, someone else would create one.