Encrypted disk images are read only in nautilus but not via shell access

I created a disk image with "Disks", without the "read only loop device" option.
I formatted the disk image as ext4 encrypted, and mounted it.
Accessing the mount point under /media/username/mountpoint with a terminal as the same user as the one running nautilus, let me do every file and directory operation.
Using nautilus I can only delete files in the mounted volume.
I can't create or copy files or directories, I got the error:
Error while copying to "VOLUMENAME".
The destination is read-only.

$ lsb_release -rd
Description: Ubuntu 14.04.1 LTS
Release: 14.04

$ apt-cache policy nautilus
nautilus:
  Installed: 1:3.10.1-0ubuntu9.3
  Candidate: 1:3.10.1-0ubuntu9.3
  Version table:
 *** 1:3.10.1-0ubuntu9.3 0
        500 http://it.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1:3.10.1-0ubuntu8 0
        500 http://it.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: nautilus 1:3.10.1-0ubuntu9.3
ProcVersionSignature: Ubuntu 3.13.0-37.64-generic 3.13.11.7
Uname: Linux 3.13.0-37-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Oct 7 18:35:40 2014
GsettingsChanges: b'org.gnome.nautilus.list-view' b'default-column-order' b"['name', 'size', 'type', 'date_modified', 'group', 'where', 'mime_type', 'owner', 'permissions']"
InstallationDate: Installed on 2013-10-12 (360 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
SourcePackage: nautilus
UpgradeStatus: Upgraded to trusty on 2014-06-10 (119 days ago)