iTunes Match songs greyed out in Remote app

I have an old MacBook Pro running all up-to-date software (10.9.2 and iTunes 11.1.5) that hosts my music library. I subscribe to iTunes Match and all my music is in the cloud on that machine (i.e. not physically on the box). I can Screen Share to the machine and AirPlay any song I want to any AirPlay speaker I want. However, when I try to use the Remote app on up-to-date iPad or iPhone (iOS 7.0.6 and Remote v4.1) to play songs that are not physically on the box, the songs are greyed out in the Remote app.

The issue originally appeared to be intermittent but now, it's consistent. Has anyone ever encountered this issue?