Filtering by "---" in Owner column doesn't display any result in WikiManager Live Data table

STEPS TO REPRODUCE

1. Login as Admin
2. Create some subwikis
3. (Optional) Grant Wiki Creation right to an user and create also one or more subwikis with the user
4. Go to Drawer > Wiki Index
5. In Owner column, filter by an username
6. Click on filter box, then click on "---"

EXPECTED RESULTS

All entries from this Live Data table are displayed back.

ACTUAL RESULTS

When selecting "—" from filter box, no entries are displayed.