Attachment Macro - Filter by label is not working

Steps to Reproduce

1. Create a page.
2. Attach two files to this page.
3. Set a label to one of the attachments (e.g. "test")
4. Edit the page and include an attachment macro to it. Under "Attachment Label", set "test".

Expected Results

The macro will return only attachments with the label "test".

Actual Results

All attachments are returned by the macro.