Previously, users could use the song identification feature by pressing Cortana's music icon while a song was playing. But now, because Cortana doesn't have the Groove library to check songs against, it says "Song unrecognized" and informs the user that the feature has been retired. Jason Deakins, a Microsoft software engineer, discussed the issue in response to a Twitter user.

Hi John. What you are seeing is expected. Due to the shutdown of the Groove Music service Cortana music recognition has also been retired. — Jason Deakins (@JasonDeakins) January 3, 2018

It makes sense that the lack of a music library would make the song identification feature unusable, but Neowin points out that the popular song recognition app Shazam is not available on the Windows Store. This means that Windows users no longer have a tool to identify music. It's certainly not a great situation for anyone who used this feature regularly.