Preconditions:

• Added 2 products (one with Availability available, second with Availability not available)

Steps to reproduce:

1. Log in to back office.
2. Go to Product catalog / Catalogs.
3. Start creating a new catalog.
4. Click on "Filters" field group (left side of the page).
5. Start adding Availability filter.
6. Select an option 'Unavailable' and save the filter.
7. Verify filtered products in Products list.

Actual result:

See attached screenshot.

Availability filter functionality does not filter products properly.

Expected result:

Availability filter works properly.

NOTE:
Availability Available filter works as it should (added screenshot2 as confirmation).