Attachment collection issue: Flexi-task vs. send notification

Hi

I generate a string of attachments that is semi-colon (as specified i the documentation for send notification attachments) that could look like:

https://staff-action.eg.dk/sites/recruitment/Recruitment%20Docs/Interview%20guide%20%201st%20interview_EN.DOCX;https://staff-action.eg.dk/sites/recruitment/Recruitment%20Docs/1.%20samtale%20-%20interviewguide_DK.DOCX;

When this variable is used on send notification it works, using same variable on a flexi-task doesn’t work.

Is this just how nintex designed it? (looking completely baffled) 

Essentially collections work on sand notification but not flex-tasks.