I found otherwise, the bass is OK generally, the problem is that C plays as E minor, and if you play C minor you get Eb major. Playing minor gets you the relative major i.e E minor gets G major. Therefore the C maj 7 accomp is not being converted to the required C major properly.

The bass problem is different; many patterns have a root and fifth, with the fifth a fourth below the root. The pitch point of these come out as E, which is correct if you don't play below C, since E is the normal lowest note of a bass guitar or double bass. But if you play E you have a B playing, a fourth below the lowest bass note and it starts to rumble too much. The pitch point is better moved to A to avoid this problem.