The static design is made up of several EDIF, NGC and DCP files.
When I load these netlist files one by one into memory and complete the first configuration run to pr_verify, pr_verify fails on GND nets:
This does not occur if I merge the static netlist files into one DCP, load this DCP into memory and then run the subsequent flow with exactly the same scripts.
This issue is caused by a failure to lock the static GND net correctly.
It is fixed in the 2015.1 release of Vivado.