I see that J.K. Rowling is releasing the third book in her detective series - the one written under her nom de plume.
"Career of Evil" by Robert Galbraith. My library has it on order. I've "recommended" (it's a function in OverDrive) that they purchase the e-book. 
My WA eBook library does not show this when I did an advanced search. So far I have not found any books doing an advance search that were not found doing a regular search.
Second, when you do the advance search, make sure that you select the option (it is probably at the very bottom of the screen just above the search button) "
Additional Titles to Recommend." This is the option that searches OverDrive's complete database, and not just your library's purchased titles. That should bring up any title that is available for your library to purchase. Now, whether they choose to buy it is another issue, but at least you will know if OverDrive has it.