This issue isn’t exclusive to Vengeance or to subclassing. I’ve opened the armory to half-empty slots I know are filled before either was introduced. It was only partly empty, as your screenshot shows - gear is there, but skills and CP are not.

It was definitely not a great experience to think the missing parts were lost from the saved build, and it was still frustrating not to be able to access them repeatedly once I understood they were still there but the server or client was having trouble populating them.