I cannot see Database Filters block if a database is set to Show records like articles. When I change the database to show a record list, then the block appears.

How to reproduce on a fresh install with default Articles database

1. Add a Yes/No custom field to the database and enable Allow filtering
2. Add Database Filters block to the page via Block Manager. Block is shown.
3. Change the Database index to Show records like articles. Block disappears.

 

It’s working as intended. I had a discussion about this with Matt years ago. 
So, it might better be feature request.