[xubuntu] 14.04. Mounted USB drive shown in Thunar, files not shown

Welcome to the forums.

The way that file managers mount drives isn't a "real mount". They use a FUSE technique and gvfs. It is often convenient for drives that aren't always coected, but there are issues (permissions/performance/access) with this. Using the /etc/fstab is the normal way to make permanent storage available on a Unix PC, but that isn't always as convenient. Also, there is a tool called autofs which can mount storage on-demand, but it is more complicated to setup. I use autofs for all USB storage. Both fstab and autofs mounts are "real" and provide complete control over the mount options, permissions, and give the fastest performance available.

The issue could be any of a few different issues. Just guessing ...
* wrong driver for the storage is being used
* missing dependencies for the file manager to access the storage
* missing file system support for the type of file system on the USB drive.

Before we get too far ... lets try something simple .... open a terminal, inside there run thunar. Are any error messages shown? Please post those back here.

If that didn't work, lets see what we can see about this disk. These will all be terminal commands. Please copy/paste the command AND the output back here, so we can see what is happening. Also, please use "code tags" so the output lines up - we prefer reading it that way.

First, unplug the USB from the system, wait 10 sec, then plug it back in, wait 10 sec and run dmesg | tail -n 20. Post those results here. We want to see something like sdb ... device added Could be sdc, sdd, sde, sdf ... depends on the number of storage devices already coected.

2nd, if the device is recognized, run sudo parted -l - so we can see the partitions on the disks and the type of file system. Post those results here.

If that showed partitions on the USB device, great! Now we know the file system type and can load the correct dependencies so it can be accessed. Don't know which packages to install until we see the dependencies and you tell us which file manager is being used. I'll await your reply.

Ref: https://en.wikipedia.org/wiki/GVfs