List File Associations in macOS Sierra

I have run into a problem where a file, that is a package file (directory that should appear as a single file), is not properly associated with its app. Files created by this app appear in Finder as a directories instead of an individual file. Re-installing the app, rebooting, and recreating the file all do not appear to help and since it appears to Finder as a directory, you cannot manually force the association through the Get Info panel.

Is there a way to view all of the file associations established in Sierra? Does anyone know of a command line tool or system file that can be edited in order to manually create an association with a packaged file?