Mojave plist error: Path had bad ownership/permissions
Solved. On the new Mac Mini my primary storage is a RAID array of SSDs in a Thunderbolt enclosure. This external storage was marked as ignore ownership.  So, even though it appeared to me to have correct ownership and permissions, when viewed as root everything was owner _unknown,  group _unknown. 

When ignore owner was turned off and the proper ownership was applied everything was functional again.