When creating a new operating system installation media created by the user does not show up in the list. However, upon saving and going back to edit the new operating system the custom installation media can be added. This may have to do with an operating system family being assigned to the installation media and then the drop down not causing the form to be updated.

<Dominic> jmontleon: np, I think the issue was changing the OS family doesn't cause the form to refresh.