GDN.. I never noticed that before.. I knew there were just Aux1 thru 7, but I never realized that they have Aux 8 printed on the door. I had to go outside and double check mine and it is just like the pic.
There is no place to plug in an Aux 8.. I guess you could use the spot marked "Aux 8" for the "AuxEx" relay that can be added if not using solar.
I suspect the real reason is to just to add to the confusion of their manuals...
My... as GND has stated the unit comes with only 8 total relays, none of yours are missing.