HI
1.what are 2 groups missing ?
build-in group(remote desktop users) or your created new customized group
2.what's characteristic for the missing group ?
The group name must meet the following requirements:
Must not exceed 256 characters
Must not end in a period
Must not include commas
Must not include any of the following printable characters: ", /, \, [, ], :, |, <, >, +, =, ;, ?, *, @
Must not include characters in the ASCII range 1-31, which are non-printable
3.what's time did you first disover this issue?did your w2016 work fine before ?
4.is your issue server 2016 joined to domain ?
5.did you try to create a new local admin account on this issue w2016 and logon by using this new local admin account then check if the same issue happen on this new local admin profile?
6.if the problem persist ,can we run below command in command prompt(open as admin)then check if it can find and solve system file issue?
sfc scannow
dism /online /cleanup-image /scanhealth
dism /online /cleanup-image /restorehealth