I recently upgraded from 16.04 to 18.04. Most of the things seem to be working normally. But when I insert a USB pen drive it does not show in the file manager as it used to when I was using 16.04. The system is already updated using the UCare system updater. I can mount and unmount it using the terminal but I would much prefer a GUI solution. I have searched the internet and also LXDE forum but could only find different suggestions bit not a specific solution. Please help.