You could be seeing "not available" next to the Total Run Cost for one of the following reasons:
1. It takes 24-48 hours to populate cost information after your submission has completed.
2. Terra can only display billing information for certain billing projects it has access to. A feature is being created to allow you to grant Terra access to view your billing account information, which will allow it to be displayed in the portal. We will keep you updated once this feature is released.
If you have waited 48 hours and still do not see billing information, follow this tutorial to retrieve it.