As of Service Pack 2, Vectorworks 2017 is compatible with Mac OS 10.12 Sierra.
Versions of Vectorworks 2017 prior to Service Pack 2 had not been properly tested with the public release of Mac OS 10.12 Sierra.
Because Vectorworks is released before the next Mac OS is officially released to the public, official support for the new Mac OS cannot be established yet. Once the new Mac OS has its public release, Vectorworks Inc. will perform its testing and make an official statement about support of the new Mac OS.
If you are running Mac OS 10.12 Sierra and Vectorworks 2017, please make sure you have upgraded to the most current version of Vectorworks 2017.
More information specifically about Mac OS 10.12 can be found here.
An operating system compatibility chart can be found here.