deletion of an item after giving feedback

*I don't know how much of bug this actually is, but I believe it needs to be fixed*

**Gorse version**
0.4.5

**Describe the bug**
For example I added a book that has a 'Game' label
This book may appear as a recommendation to someone with the 'Game' label on it, but the moment the user gives feedback to this book, the book disappears from the list of recommendations.