Client Online count is wrong in the Home Screen > Endpoint Status, and may sometimes show a negative number.
Windows 10 clients
Windows 10 clients are sending the incorrect OS type value to the SEPM causing them to not be counted in the status.
This issue is fixed in Symantec Endpoint Protection 188.8.131.52 (RU5) For information on how to obtain the latest build of Symantec Endpoint Protection, see Download Symantec software, tools, and patches.
SEPM receives registration data from SEP agents on 'Windows 10 Pro for Workstations' where the OS Type value is -1593180158 instead of 2701787138.