That's just a false indication whenever you remove all the documents from a page (but not everything the collection contains).

Steps to reproduce:

• fill a collection with P*20+1 documents, where P>1 and 20 is the number of docs displayed per page;
• navigate up to the last page, so that only the last document will be visible;
• remove it with the "trash" button;
• at this point the page says that the collection is empty, but it actually contains P*20 docs.

The pager is also incorrect: still indicates as before the deletion.