I have had a similar problem. The master file has randomly shifted location, so when I reload the references (including survey file with correct location), the content of the master file is stranded far, far away in space. I have an entire drawing set of sheets in the master file, and now the viewports on every single sheet are empty and must be recreated.
This is absolutely unacceptable performance from Vectorworks.
If anyone can help, I'll be most grateful. Thanks.