Verify that you have selected the title inside the collection by following these steps:
To see all of the results for the same title, uncheck the box next to "limit by my selected collections" and search again. The collection that you have selected in this set of results may display. If so, can click on the collection title. This allows you to search for the ISBN or ISSN from inside your selected collection.
For non-knowledge base titles not showing in Discovery unless you search "Libraries Worldwide," see: Why is an item my library holds not showing as held in Discovery?