Adding "File" Deletes all other unsaved meta box data

When adding a file to a custom post type along with adding info in additional meta boxes on the same post, all unsaved additional data is not recorded in the database when clicking publish or update, aside from the file. If you have updated or published the post first, data will not disappear, but you cannot add additional meta box data at the same time as adding a file or only the file saves.

https://wordpress.org/plugins/meta-box/