When you control a "Spikeroot Automode change (SquadId: 2000856) on the map Titans and put it into a control group it will show (in my case) as a Magmahurler. It is shown correctly as a Spikeroot when in a control group on his own.
I have experienced this behaviour not only on this combination of mind controlled PvE units. It seems that only one type of PvE unit gets an image in the control group. The number of units is displayed corretly, it just shows one icon for all different mind controlled units.