AdjustTokenPrivileges Failed with Error 1300

SNMP Service is running under "Local System" account.Its token includes the NT AUTHORITY\SYSTEM and BUILTIN\Administrators SIDs; these accounts have access to most system objects. Already it's having Shutdown Privilege.Then why it's throwing ERROR 1300??

I am running an SNMP Agent on WIN10 (patch level 12/2017) and wrote a function to list all token privileges using GetTokenInformation() within my extension DLL.
I always get:
INFO: Having privilege SeSecurityPrivilege 00000008 State:0x00000000)
INFO: Having privilege SeDebugPrivilege 00000014 State:0x00000003)
INFO: Having privilege SeChangeNotifyPrivilege 00000017 State:0x00000003)

In Windows 10 we have "Windows Service Hardening" (WSH) active.
See: http://www.itprotoday.com/management-mobility/understanding-windows-service-hardening
I am able to add the SeLoadDriverPrivilege privilege using:

sc privs snmp SeChangeNotifyPrivilege/SeSecurityPrivilege/SeDebugPrivilege/SeLoadDriverPrivilege

I can verify this by:
sc qprivs snmp 1024

as also in Registry
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SNMP\RequiredPrivileges

But the strange thing is that GetTokenInformation() within my loaded extension DLL does not show this new privilege!?!?!

I looks to me like MS has hardcoded the privileges within SNMP Service
(at least when loading extension DLL´s)

Any ideas ?

Here the code to read out the current active privileges:
DWORD dwLen = 0;
TOKEN_PRIVILEGES tp = { 0 };
GetTokenInformation(hToken, TokenPrivileges, NULL, 0, &dwLen);
if(dwLen > 0)
{
BYTE* pBuffer = new BYTE[dwLen];
if (pBuffer == NULL)
{
return FALSE;
}

if (GetTokenInformation(hToken, TokenPrivileges, pBuffer, dwLen, &retLength))
{
WriteAppLogFormat(L"INFO: GetTokenInformation returned Len=%d)", retLength);

TOKEN_PRIVILEGES* pPrivs = (TOKEN_PRIVILEGES*)pBuffer;
for (DWORD i = 0; i < pPrivs->PrivilegeCount; i++)
{
WCHAR Name[100];
DWORD Size = 100;
LookupPrivilegeName(NULL, &pPrivs->Privileges[i].Luid, Name, &Size);
WriteAppLogFormat(L"INFO: Having privilege %s %08X State:0x%08X)", Name, pPrivs->Privileges[i].Luid.LowPart, pPrivs->Privileges[i].Attributes);
pPrivs->Privileges[i].Attributes |= SE_PRIVILEGE_ENABLED;
}
}
else
{
WriteAppLogFormat(L"ERROR: GetTokenInformation 2 failed. (0x%08X)", GetLastError());
}
}
else
{
WriteAppLogFormat(L"ERROR: GetTokenInformation 1 failed. (0x%08X)", GetLastError());
}
...