Is it true/are you sure that there is not the USB parent device down at the bottom of the widget?
I thought I checked both 4.2 & 4.3 before this question :
My main USB storage shows under the name of the maker of the SATA USB converter… so not easy to identify, but it is there, lonely and dislocated from its babies.
[Edit:]
Question for @freeflow : are you able to see the name of the USB device for your partition(s) -anywhere in the widget?
Maybe it can help to open terminal in sys-usb, and run lsusb only to find the name.