Trying to turn on owid-grapher's local server, I get "Waiting for MySQL to come up" forever and localhost:8080 doesn't return anything

Question

I wanted to experiment with Our World in Data's Grapher. I followed the local development setup instructions. Most of the code worked. The Docker container is up. I can access the MySQL database with DBeaver. The docker tab in tmux says:

...
db-load-data-1  | ✅ All done, grapher DB is loaded ✅
db-load-data-1 exited with code 0

The welcome tab correctly displays:

Try these url's to see if your environment is working:
    https://localhost:3030/  <-- a basic version of Our World in Data
    ...
    https://localhost:8080/wp/wp-admin/  <-- the WordPress admin interface
...

However, the admin tab says:

Waiting for MySQL to come up................................................

Also, the localhost websites are not responding when I try accessing them in the browser.

Has anyone here worked with owid-grapher before that can help me?