Gigalixir - phoenix app, assets are 404

Hi
I’ve put together my first phoenix project that got to a stage that I’d like to deploy it. I’ve chosen gigalixir as it sounds perfect. I’ve done the setup and deployed it - I can access it in the browser and it works, but all the static assets (css, images) are 404 not found.
I’ve run MIX_ENV=prod SECRET_KEY_BASE="$(mix phx.gen.secret)" mix phx.server locally to see if that works and that does. I’ve noticed that locally the assets have a hash generated as a suffix and that’s what the html has, but in the gigalixir deployed html it doesn’t have those hashes, so I assume it’s something to do with that but not sure how to proceed. Any tips are appreciated