7.6 Installer Missing Software Sources

Greetings

I've recently downloaded RHEL 7.6 and written the ISO to a USB to install on a server. The installer starts correctly and everything appears to be kosher all up until the configuration process. The Software Sources selection is clearly pointing and the USB drive, and the DVD packages are on it. However, the Software Selection section is completely empty, and I'm unable to determine why. Has anyone experienced this?