Not on mine. I can add or remove cells to/from the most positive end anytime even when others are connected and it just reads more or less cells on the next pass.
Not sure if mine looks like yours under the heatshrink/label, though it probably does.
Most likely the difference is in the programming, since yours reads cells regardless of which pins they're connected to, right? So all the hardware has to be working, just the MCU doesn't display them all?
Though...I havent' done a completely conclusive test, using 8 cells that I know are significantly different in voltage, all at the same time in a row so I can see that it is actually reading each individual cell and not repeating a measurement somewhere; it does appear to be working becuaes I get 8 readouts before it restarts the cycle.
I don't normally use them for 8s; I just tested it after seeing your post, on the EIG pack (that stays well-balanced on it's own) on CrazyBike2. The plugs are all 6s on there cuz that's what the Battery Medic and other RC type stuff I have for checking can all handle, so I'd usually just plug one into each of the first two 6s ports, and leave the 2s final one unmonitored, or use a different unit (I only have two of the kind above). Until this post came up it didnt' even occur to me to try them as 8s.