Welcome to the Humminbird Side Imaging Forums Austin358.
It could be but the first thing that I would check would be if the AS-Si-DB-Y cable is connected correctly (I have reversed these, several times…) and if the transducers are fully plugged into it.
When you installed the XP-9-20 shoot-thru-hull (inside-the-hull) transducer, did you perform the on-water testing?
There are no options for using the shoot-thru transducer. You should leave the transducer selection menu set to the Hi-Def Sidescan setting.