You imported using the filename instead of internal metadata.
Not to worry, but let us fix the setting for the future.
Preferences: Adding books: Reading Metadata (the default on open tab): Tick
Read Metadata from file contents...
OK, now that is done.
(we will do a test case first)
open the MDE (tap E ) for any of those books: click to select the format on the right: Click the blue bool slightly to the left.
Success? (you can make additional changes) Click OK
OK, now we will go for Bulk mode: Select all the books that need this help:
Tap E (MDE is now in Bulk mode): On the Basic Metadata form: TICK the box
Set Metadata (except cover) from Book files (OPTIONAL to set the cover: tick the
Set from e-book files in the Change Cover area
click OK
