Can't delete files in manager mode

I have a listing of a subdirectory displayed with this shortcode

[fileaway sub="subdirname" manager="on"]

When I login with a role which has previously been set up in manager mode I can’t delete files from the listing. When I click delete and then proceed I get this error:
“Go directly to jail. Do not pass GO. Do not collect $200 dollars.”

I’m pretty sure it used to work, and the thing that’s changed is that I’ve upgraded to 4.0.

The page is password protected, so I can’t put a link to it here.

https://www.ads-software.com/plugins/file-away/