FYI...

On linux especially it won't eject a mounted drive, mounted drives are ones you can see.
if an application (windows or linux) is hadeling the device by it'se self, such as a cd burner piece of software...

then an incorrectly closing application (i.e. erroed when closing or just badly made / a bug in the software)

can cause the pc to belive it's in constant use so won't eject the cd