After reissuing the license on a server with multiple IP addresses due to a "license validation failure" the Licensed IP address: displayed in the Account Information section of that package switched to a secondary IP.

I used the FQDN in the
/home/centovacast/system/runascc/runascc exec ccmanage reissuelicense newhostname.com
command; DNS (and /etc/hosts) point that host to the main IP address.

Any ideas on how this happened and how to switch back to the correct IP address?

This is an issue because the email notices from Centova Cast on that server are designated as spam due to SFP failure.

Centova Cast always just uses the default outbound IP address on your server so if it changes, you will indeed need to reissue your license.

Typically this is managed by your OS distro's networking scripts automatically, and can change if you do things like adding/removing IP addy's on your server.