The following works for me when I plug in my Samsung Galaxy phone but after the post bymuungwana not certain if this will help but it only takes a minute to check it out,
Config Your Desktop > Hardware > Removable Devices -
Configure automatic mounting of removable storage media - with the following options
Enable automatic mounting of removable media
Only automatically mount removable media that has been manually mounted before
Mount all removable media at login
Automatically mount removable media when attached
You may want to remove the phone, enable appropriate setting(s) and then restart your desktop and then plug it in again