In the clean cpanel installation, the ethernet device setting in the basic config section takes a null value. Therefore, there are problems in recognizing additional ip addresses, it is necessary to change the setting here each time.
Internal case CPANEL-24394 is open to address an issue where the ETHDEV value in /etc/wwwacct.conf is blank upon the initial cPanel & WHM installation. The planned solution will ensure the first non-loopback ethernet device is setup by default for the ETHDEV value during the post installation setup. I'll update this thread with more information on the status of this case as it becomes available.
To update, CPANEL-24394 was published in cPanel & WHM version 76.0.20:
Fixed case CPANEL-24394: Added the first non-loopback ethernet device as the default ethernet device used by cPanel during the post installation setup.