Help using open file with app action

My apologies for a dumb question, because I’ve gotten this to work before, but now I can’t. I’m trying to create a keyboard shortcut to open a file highlighted in Windows Explorer with a specific program. In my case, I’ve created the shortcut “Alt-M” to open a file with “mupdf-gl.exe”. When I activate Listary with “Alt-L”, I’d like it to be prepopulated with the currently selected file’s name, but Listary opens with a blank line. I thought I got this to work before on a previous computer, but maybe my memory is faulty. Any suggestions?

Hi, can you upload a screenshot of your custom action setting or paste it here?