Comment 89 for bug 1314556

Ruslan (#80) solution worked for me:

"For KDE users experiencing a similar issue, make sure that either Amarok isn't running or its MTP plugin is disabled."

I am not a KDE user, but I was running Amarok - listening to it while I tried to sort-out my 'phone.

It lives in my system-tray (whatever). Would never have guessed that it was the source of the problem

Thanks very, very much for taking the trouble to post.