Not sure if the issue relates to Pro 6.4.11 but I have picked up an issue after updating.
The site was built in 2019 by a staff member and I haven’t needed to edit much since it was built. We’ve had a few issues and I needed to fix some stuff in the headers.
On going to the headers / footers it seems that, while the pages are working, the assignments have vanished from Cornerstone. Most of the headers / footers have no assignments and the ones that do have assignments seem to have partial assignments (or conditions that are empty).
I’ve provided access just in case you want to look.