In the same vein as the definition query, it might be a symbology thing making it invisible. If your attribute is a different value than what your symbology draws and you have unchecked 'all other values' from showing up then it would be invisible.
Not in this case, as it disappears from the attribute table as well.
I believe we have found the issue. A coworker and I have been going back and forth editing shape files; I am using Arcmap and she is using Autodesk Map 3D. After exporting the shape file as a new shape file, and replacing the links, everything seems to be working ok. If anyone has any other tips, tricks or experience going back and forth between the two programs, I'd love to hear it.
Thank you for your other suggestions.