A client's actual OS would be "Windows Server 2016 Standard Edition". This shows correctly in the client properties, however if a "Computer Status" report is run, the OS will show as "Windows Server 2015 Standard Edition".
No errors are displayed.
SEP Client 14x
SEPM version 14 RU1 MP1
This is a Known issue and Symantec is aware of the problem.
Please upgrade both client and SEPM to 14.2 RU1 or newer.