libkf5solid5 does not handle multiple mount points (there is a "Fixme" in the source code) and also does not check if the mount point is a bound mount. Unfortunately udisks2 sorts mount points alphabetically (or so it seems) So if the bound mount points path name is alphabetically lower than the mount point of the partition root the former will be used instead of the root mount point.

How to reproduce:
boot kubuntu 15.10  live dvd (KDE Frameworks 5.13.0)
sudo su
mkdir /mnt/test
mount -t auto /dev/sda1 /mnt/test
mkdir /home/kubuntu/test
mount /mnt/test/somedir /home/kubuntu/test -o bind
open for example Dolphin
clicking on the device name opens /home/kubuntu/test (/mnt/test/somedir) instead of /mnt/test because udisks2 lists /home/kubuntu/test before /mnt/test and libsollid onyl regards the first mount point