When I add an IP address through the "Add a New IP Address" section, I do not see this added to my interface configuration file. I do see a dev:cp#, is this a temporary assignment?
cPanel utilizes the kernel module IP aliases, which adds the IP to the network interface, so these would not be temporary. IPs are added to the /etc/ips file instead. You can read more on the function of this through The cPanel Service Daemons and kernel alias documentation.