Hi Drew,
Yes, you are right of course, a md-file is basically a text-file.
However, I wanted to send one of my notes to a friend, who asked for the md-format. So I copied the note as Markdown-file and pasted it to the root folder of my iPad. There it was pasted with the txt file extension. Because of that I tried some other notes using the same copy/paste procedure. Some were pasted with the txt-extension others were pasted with the md-extension. All notes I tried, are just text with some simple markdown-formatting, nothing fancy. I then exported the same notes via Agenda’s “share as markdown” feature. Same result here.
There were no other apps involved except Agenda and the iPadOS file browser.
I hope that gives you a clou about what happened and what the problem could be.
Best regards Helmut