Why is the convert button greyed out?

[alirz1]

As seen in screenshot. I want to convert a mp3 file to aac
I upload the file, make the convert to selection. But the convert button is still greyed out

[Trithereon]

To reproduce this bug (I am using the :main docker image), I can...

1. attempt to upload a folder
2. remove it from the file list
3. upload a proper file to convert
4. button is grayed out every time

A refresh of the page instantly restores functionality.