[Adoby]

You can set a lot of options to modify the ePubs in different ways.

You typically select the ePubs you wish to modify and then run the plugin.

So the update of metadata in books inside the Calibre library is not automatic. If you feel a need to look at the books inside the Calibre library, then you are most likely using Calibre the wrong way.

The metadata is automatically updated whenever you use Calibre to save or send a book.

The reason for this behaviour is that it would be very slow and inefficient to update the metadata inside the ePubs every time you change the metadata. The books would have to be copied, unzipped, modified, zipped, replaced and deleted for every tiny little change. Calibre would be unusable. It is much faster to only update data in the database metadata.db, and update the actual books only when they leave the library. An exception to this is when you use the OPDS server in calibre. You may then wish to use the Modify EPub plugin to make sure the metadata inside the ePubs is updated.