To start, try it on a 1-player, 2-player, 3-player, and 4-player game. Same symptom for all? Also, is the end-of-ball bonus scoring normally? If you are still on B1P1 after it kicks out, and still scoring normally, there is a First Ball Relay that is supposed to trip when any score has been made. Look for that on the schematic.
.................David Marston