It certainly looks like it was immediately replugged ( which should not happen ). Can you try with a different usb stick? And/or after upgrading to 15.10 since 15.04 is now deprecated and will reach end of life soon.
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to udisks2 in Ubuntu. https://bugs.launchpad.net/bugs/1507183 Title: "safely remove" remounts after a couple of seconds Status in udisks2 package in Ubuntu: Incomplete Bug description: Ubuntu 15.04 Release 15.04 fresh install Selecting 'Safely remove' on a USB drive shoudl than required it to be re-plugged in to be freshly detected and mounted. I'm seeing this only temporally remove the drive and within a few seconds the device is re-mounted. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/udisks2/+bug/1507183/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp