On the album info page, depending on how you navigate to the page, the buttons at the top can be missing the Favorite (heart) button and the More (M) buttons.

I see this issue with missing buttons going back to at least 7.6.

Additionally, in 7.9 the Add (+) and Remove (X) buttons are broken when this truncated set of buttons is displayed. If there is anything in the current playlist, the Add button fails to do anything. It only works correctly when the playlist is empty. The Remove button sometimes works correctly, but I've also seen it remove items from the current playlist and replace them with the next N tracks from the album. If there's one item, it removes it and loads one item, when two items are in the playlist, they're replaced by two new items, etc.

To get to an album info page with the missing and broken buttons: Navigate to any track info page, then click on the album link that appears to the right of the coverart.