Hi Whitecolin11,
The actual reason for the behavior described (always Bass note C for all chords played in the Style Control range of the keyboard) is that a MIDI template is selected, where one or more channels are selected for input of the Style Bass note via a MIDI pedal in the "BASS" tab. This is e.g. the case with the "MIDI Pedal 2" template. However, if no MIDI note is received on one of these channels specified here, the Bass note C will always be played, as in your case. Also see the attached screenshot.
The easiest way to fix this "problem" is, as already mentioned by Eileen, to set the standard MIDI template "All Parts". Alternatively, you could also use the "KBD & STYLE" template. These two templates only differ in the way the keyboard parts are sent externally via MIDI (which is irrelevant for normal playing).
So go to "Function > MIDI", select "All Parts" or "KBD & STYLE" and press the EXIT button to close the MIDI display. This is the only way to save the selection made in the System Setup, and the set MIDI template is automatically loaded with every restart.
Hope this helps!
Best regards,
Chris