So if I have an existing markdown file in Dropbox, Kodex can open and edit it no problem. But if I duplicate a markdown file in Kodex, it becomes "filename.md 2.txt" and the renamer has no way to edit the file extension.
In any case, the renamer doesn't work because Kodex can never "communicate with a helper application" ie Files.
Which makes the whole exercise completely pointless.
And this is why I despise the approach that Apple's taking with filesystems. This BS is slowly creeping into MacOS as well.