Direct database search works so put a letter such as “a” in the search box then click direct database search option and search again.
You should be able to find a few sample artist and albums, try the following.
http://127.0.0.1:5000/artist/0eedfc95-e79a-4fd9-832a-cd816a0b3fda
http://127.0.0.1:5000/release/25959c11-aac6-4bdd-bab9-5e6eba4e9c70