I thought this was odd, and I can't find any articles online or in the forums that Pandora got rid of them.
I do not have my Thumbs-Up and Thumbs-Down buttons on any of my devices; Home Computer, Work Computer, Android Phone, and Android Auto interface in my car for Pandora are all missing both the Thumbs-Up and Thumbs-Down buttons.
I still have my "Thumbs-Up" playlists, just can't approve/disapprove any more songs. Any help would be appreciated. thanks!