A standard report for getting the information on unfillable holds is almost impossible. The problem with the one we had in workflows is that it would only report titles that had one copy on the record. It wouldn't show titles that had 2 missing copies, or 41 available copies and one missing. Just titles with one copy would be found.
The one we had in BC Analytics was reporting any title that had at least 1 missing/lost/discarded copy on it. Even if there were 41 available copies on a title, you'd get it in your list.
The solution is a little messier, but I think it works. Use this link and you should be able to view a report listing all the holds that have unavailable items. - Items with unfillable holds. On the right side of the page, select your library to view your holds on titles with no available copies. You'll see the item count as well. Below the unavailable copies, are listed the available copies, so you can tell if you have a hold for Maus, there are 5 unavailable copies and 9 available ones.
You can copy a barcode from the list by clicking on the cell with the barcode and clicking the ctrl and v keys on the keyboard, or right click on the cell and select to copy cell. You can also print the page by using the browser's print option in the menu on the upper right.
We'll put a page with the link to this report in the g-drive. I hope this works for you. Please let me know if you have any other ideas.