@Merischino
I'm a bit nervous about poking my nose in here but I'm going to try anyway...
Can we go back to basics and try a very simple task.
- Choose a book which has incorrect metadata.
- Press e to edit and correct all metadata for this one book. Press OK to save changes. (I believe it is at this point that changes are commited to metadata.db)
- Immediately press e again to relook at the metadata for this book. Is the metadata still correct?
- If yes. Close down Calibre completely.
- Reload Calibre and find the book again. Press e again and look at the metadata for a 3rd time. Is it still correct?
The above should tell you whether your changes are 'taking'.
P.S Do not do any Converting or Save-to-Disk.