[ubuntu] Ubuntu won't always show disc that was inserted in CD-Rom

Before I upgraded to Ubuntu 16.04, I bued some discs with Ubuntu 14.04. The contents of the discs is just data and pictures. When I insert them into the CD-Rom tray with 16.04, the light on the optical drive lights up, and I can hear it spin for a couple seconds, but then it stops. The disc contents are not available for me to use, and no icon appears in the menu bar. If I take the disc and put it in a different computer that has Ubuntu 14.04, it works just fine.

This doesn't happen on all CDs. But a good portion of the ones I have are unusable unless I go to a different computer.

Please help!