Hey @alexmercer
Thats just a warning, Graylog just yelling about the OS system config.
You can look at you NXlog logs on the Window server 2016 maybe that might help.
So is the issue your not see the logs on the GUI? Perhaps check your timezone/Dat & time on both GL server and Windows 2016 server. just an idea.
Here ar ecouple links i forgot to add earlier for anyone having this issue.