This only is the case when right clicking on an individual track in Apple Music. You can still play whole albums. It's very frustrating when you want to add a new song on the fly.
iMac Pro
That issue has been recently fixed. You may need to be on Big Sur 11.2. for that to work, although it's not clear whether this might have been fixed in the background. Here was the discussion on this topic: PLAY NEXT • PLAY LATER option missing in Music App on Mac
However, there are more issues currently plaguing the Music app. Such as this one: Cannot change order of songs in "Play Next" queue
That issue has been recently fixed. You may need to be on Big Sur 11.2. for that to work, although it's not clear whether this might have been fixed in the background. Here was the discussion on this topic: PLAY NEXT • PLAY LATER option missing in Music App on Mac
However, there are more issues currently plaguing the Music app. Such as this one: Cannot change order of songs in "Play Next" queue
Can you no longer add an individual Apple Music track to the 'Play Next' queue?
