Creating alias/shortcut to private files not possible

Hi everyone,

We are using the fair allocation plugin with moodle 3.9.17+

Our scenario: When creating choices, we would like to attach a PDF file for each choice from the private files via alias/shortcut.
However, when clicking "save changes" the file disappears.

Can you check why the alias isn't working? If you need further information I am happy to provide it.

Best wishes, 
WireLiz