Before a partition in Ubuntu can be accessed, it need to be mount first. By default, partition is not automatically mount. So when you bookmarked a folder from other partition, it will not be shown until that partition is mount.
Although mounting a partition is relatively quick, but it’s irritating when bookmarked folders aren’t shown. To automatically mount a partition, open up your terminal and install pysdm:
sudo apt-get install pysdm
pysdm is a Storage Device Manager. After installing, go to System -> Administration -> Storage Device Manager.
Enter your password to have root access. Once you go in, you will notice all your partition(s) on the partition list. Expand other partitions on the list. Click on each children of the partitions and then click on Apply. This would automatically mount the partition whenever you login to Ubuntu.
If you are a geek and prefer manual configuration through the terminal (instead of GUI), do take a look @ https://help.ubuntu.com/community/AutomaticallyMountPartitions
