I decided to try again, positive that I would be able to get it working like my second copy at home. When I reinstalled the software, the software remained the same, with no groups and read/delivery notifications again.

My version at work had a previous install before we switched over to Microsoft 365, but was updated to 2016 when it became available, so I opted to remove the software by: There had previously been no installs of Office there before and eureka… the correct version with groups and read/delivery notifications appeared. I installed my second copy of Office 365 on my Mac laptop at home.