When using the personalized similar books feature, there is a bug.

Expected behavior: personalized similar books list is the same for the same book across different editions (or at least similar).

Actual behavior: personalized similar books list may be empty for user added editions.

Example:

Typical book edition has a complete personalized similar books list:
https://app.thestorygraph.com/books/4c79a0ce-4dbb-4947-ba2d-bcfdff5cbc6c

For a user added edition of the exact same book, the personalized similar books list is empty:
https://app.thestorygraph.com/books/9fc79c37-f975-4681-b5b2-780bd5e83eab