How to duplicate:
- Install agda, load agda2-mode
- Open a file
Foo.lagda.md
- Write some Markdown and a fenced code block with
agda language
- Load the Agda code with C-c C-l.
- Watch the Markdown highlighting disappear.
Not sure if this is an issue in polymode, poly-markdown or agda2-mode, but I thought to start here and try to find out where the issue is to see if I could help fixing it.