I don't think this is related to the above question, but the linked "solution" is as good as I can come up with, however it looks like its possible that ALL the libraries in the collection are suffering the same situation...
our site was migrated to 2013 from 2010 from 2007 and is running in compatability mode around 6-18 months ago. I'm pretty sure the old system is gone too - database backups might be obtainable... not sure.
There are a bunch of "site columns" that are used consistently across the collections libraries (there seems to be a general avoidance of "content types", don't ask me why, I don't know, I also don't know what would be involved in moving them all to content types as many of the sites "views and webparts" use the content type columns to surface things all over the place, so I suspect it would be a big job), but folks have recently noticed that some documents are missing from various pages (webparts that are gathering documents from these columns values).
But the problem is that it seems that since the update most (all?) of the document libraries NO LONGER enforce the requirement and litterally only show "name*", and "title" in display and edit properties...
Any ideas on how to get things back to showing the "proper" forms (I can only guess what this was from documentation and screenshots and general guessing based on the "commonness" of the columns in question)? Or is there a way to merge or migrate "columns" to content types in some way that is either "collection wide" or non-breaking?
ANY assistance would be greatly appreciated!