I ran into this today. If I understand correctly the privilege drop happens before the chown though it should be the other way around, the chown should happen while root and then privileges should be dropped. And in any case the failure of chown should not prevent the logs from writing. The solution seems to be that $FileGroup and $PrivDropToGroup should match. From a security perspective setting $FileGroup to to syslog is the safest course of action.
I ran into this today. If I understand correctly the privilege drop happens before the chown though it should be the other way around, the chown should happen while root and then privileges should be dropped. And in any case the failure of chown should not prevent the logs from writing. The solution seems to be that $FileGroup and $PrivDropToGroup should match. From a security perspective setting $FileGroup to to syslog is the safest course of action.