Serial Number shows To be filled by O.E.M

Can someone please help I have used GenSMBIOS-master to input the numbers and restarted the computer and it did not fix the issue.
Whenever I open the config.plist all numbers are there (iMac15.1) but not in the system report. I have not signed into my apple account as I do not want
to create a possible issue with account.
screen shot attached