Process File Business Process element not working with SysFile

Hello,

I have some business processes that reads the files attached to a section using a "Process file" element to add them to a "send email" element.
If the "container" of the attachments is "an old one" (like CaseFile, AccountFile, etc.) it works fine.
If the "container" is the "Freedom UI SysFile" (Uploaded File) the "Process file" element always returns an empty collection of files (even removing all the filters).

How can I send an email from a Business Process and attach the files stored in "SysFile" entity?

Thanks