I just opened up a project Sheet Set that i haven't worked on in a while, and all of my layout pages have a series of "#" in place of the fields. For example, the name of my viewport should read "Head Detail", which is the name given to that view in the Sheet Set Manager, but instead reads "##############". This also happens with my view numbers, callout bubbles, etc.
However, the information in my title block is still intact. For example, the Project Name, Client Name, Page Number, etc. all read the correct values.
Does anyone know what is causing this and how I can fix it? I tried opening the drawings in Reference Manager, but I see no alerts or errors. I have had this happen before in previous versions going back to at least 2010, but they have always been small projects and I just recreated the views and callouts. This is a large project however, and redoing this will cost hours, if not days of extra work.
In examining the fields, it seems like the problem fields are those defined by the SheetSetPlaceholder Filed Name, and the Placeholder type is irrelevent; they are all broken. For other Field Names, for example CurrentSheetNumber, the references still work.
As a test, I just opened a rendom sheet that has a series of vieports showing the ##### as the view name and view number. When I drag a new view from the Model Views tab in the Sheet Set Manager, the new view generates the correct view name, and I can sucessfully change the view number in the Sheet Set manager. But the existing views remain as ######. I'm not sure what is going on...