I had the same problem described above, with File Type set to dyn.age80c6du.
Managed to fix it by:
Trying all the suggestions mentioned above (which might have helped, I'm not sure)
Following the instructions here: https://discussions.apple.com/thread/7421012 (again, not sure if needed)
Running all the Onyx maintenance operations
After doing these three things, dyn.age80c6du was set back to com.apple.application-bundle across all my apps.
Hope this helps someone.