Reinstalling only refreshes the program binaries -- all settings remain untouched in
Try renaming that folder to calibre.backup, to reset everything. Do not delete it, you may want to restore the folder if it turns out that wasn't the problem.
If you open the AZW3 (via the file browser on Drive I: ) in the calibre viewer, does it show the title correctly in the titlebar?
Or reimport the books-on-device into a test library, and see if the metadata gets determined correctly.
If the AZW3 has the correct metadata in it, there is something wrong with your Kindle.
I cannot think why calibre would delete all metadata in the book. If the metadata is missing... I don't know.