@MidknytOwl: I'm repeating some of what the others have said, but...
From the two books, the second one either has the series info in the title in the metadata in calibre, or you are using a metadata plugboard to tweak the title when sending the book.
If the series info is in the title in calibre, then you need to fix that. And make sure the series info is populated correctly.
If you have a metadata plugboard for the driver and book type, you need to remove that or change it to produce what you really want. You can see these on the Metadata plugboard page of the calibre preferences.
For the plugboard, have you recently changed between using the KoboTouch and KoboTouchExtended driver? If so, that might explain the recent change in title as the plugboards are specific to the driver and you might now be using one from some time ago.
To get the series info populated you need the following:
- Series info on the book in the calibre library.
- The "Set series information" option enabled in the driver you are using.
- "Metadata management" set to automatic on the "Sending books to devices" page of the preferences.
With the above, the series info is checked and updated whenever you connect the device. But, it cannot be set when you first send a book to the device. The book must be imported and in the database on the device before the driver can set the series info. This means you send the book, disconnect the device and let it import the book. Then connect again and the series info will be set.