Photo Sharing Preferences shows 0 photos

I recently purchased a new 27" Retina iMac and made the move from iPhoto to Photos. But now that I'm trying to pipe my photos into my living room via my Apple TV, I'm having no success. In iTunes' Home Sharing > Photo Sharing Preferences pane, when I toggle to Photos instead of iPhoto, it displays "0 photos" despite having thousands of photos in the Photos app.

Trying to access the photos via the Apple TV, in the Computers > Photos tab, I get a message saying, "To choose photos to share, open iTunes on your computer and go to File>Home Sharing." I've done this dozens of times now with no success.

I had no problem accessing my photos on this Apple TV from my old computer using iPhoto. Any suggestions?