Negated source filter excludes posts with no source

[halbrd]

A source filter such as source:*reddit.com* works as expected, returning posts with "reddit.com" in the source field.

However, try negating the source filter: -source:*reddit.com*.

Expected function: return the inverse of the above - posts that don't have "reddit.com" in the source field (including posts with no source content at all).

Actual function: it only returns posts with something in the source field (and don't include "reddit.com") - posts with no source aren't returned here.

This seems unintuitive, and more importantly, there doesn't seem to be a way to achieve the expected function.

[zaidalkaz]

This issue happens with "upload" as well - posts uploaded by anonymous users do not show up when searching for a negated filter e.g. "-upload:zaidalkaz". I suspect any "empty" field fails to show when searching in this way