SOPC Builder error:PTF failed!

At that stage it's attempting to write to the .ptf file so if there is a write permission problem then these steps will fail.

If you navigate to the .ptf file on the mapped drive, right click it, and select properties you'll be able to see the file permissions. It could be set to read only or the machine you are accessing the file from doesn't have write permission to the file. Perhaps Microsoft changed something with network file accessing that is causing this issue (not sure since I typically try to keep my project files local for compilation speed reasons).