Re: Connecting USB cable results in internal storage and SD card being unmounted
Does your phone have MTP on it as a option. If so your phone cant handle both mounts at the same time due to how its partitioned due to the update.
Do you realize that the post you responded to is over 2-1/2 years old? And not many (if any) phones at that time had MTP.
Since the OP had a phone with USB Mass Storage, it was actually acting as intended. USB Mass Storage cannot handle being mounted to both the phone and a computer, so when USB is connected, the memory is unmounted on the phone.
Conversely, MTP can handle being mounted by both the phone and the computer at the same time.