Coursepress Downloads are empty


I've raised this issue before ( and I see other people are also having the same problem (
Is there a solution for this yet?
I have done as below, to try and problem solve, but nothing worked:
changed theme
deactivated all plugins
updated coursepress
increased memory both in the config and in the php.ini
tried various different files types (they are fine to download straight from the media library, there is only a problem when using coursepress).

I would like to get this sorted asap and happy to provide access if needed.