When a project is updated from Vivado 2017.3 to Vivado 2017.4, the ipstatic folder is not being updated during the export_simulation phase of "Generate Output Products".
If the folder is deleted, then it is created correctly when Generate Output Products is run again.
To recreate this behavior:
To work around this issue, remove the ipstatic directory and re-run Generate Output Products.
This is scheduled to be fixed in Vivado 2018.2.