To everyone still having this problem: We're curious what release of Ubuntu you're using. That will give us some idea of what version of gphoto2 you're using, which seems to be the root of the problem.
Marko: One of the previous commenters reported a link that suggests this problem was fixed in libmtp, which may solve your problem with Rhythmbox. You might verify if you have the latest version installed.
To everyone still having this problem: We're curious what release of Ubuntu you're using. That will give us some idea of what version of gphoto2 you're using, which seems to be the root of the problem.
Marko: One of the previous commenters reported a link that suggests this problem was fixed in libmtp, which may solve your problem with Rhythmbox. You might verify if you have the latest version installed.
-- Jim