SUSE Linux Enterprise Server 12 (ppc64le) SP3 is installed.

I tried to register with a registration code provided by the 60 Day Subscription Evaluation, with the following command:
SUSEConnect -r <YourActivationCode> -e <YourEmailAddress> --debug

This resulted in several messages shown in the screen, the last 3 of them were:
Registered SLES 12.3 ppc64le
To server:
Using E-mail:

This also resulted in that in my session in the Suse web page, the server was added to the registered systems list.

But, apparently the server is not fully registered, as shown by the SUSEConnect command:

SUSEConnect -status-text
Error: SCC reurned 'Please provide a Registration Code for this product' (422)