The titles parameter is broken on Special:ApiSandbox.
- Go to https://en.wikipedia.org/wiki/Special:ApiSandbox
- Under action, select query
- Click on action=query
- Under prop, select revisions
- Under titles, enter Wikipedia:Village pump (technical)
- Click on "Make request"
As can be seen in the results, the titles property is there, but it is always an empty string.