Quoted from Eric_S:
I had some time today to check this out and I wasn't able to repeat it. I'm hosting our league tonight and I'll report here if I notice anything odd.
During league play, we had a four player group playing on ACNC. The first player had a ball get stuck by the upper flipper/flasher cover. The game kicked out another ball and play continued. When the ball in play drained, it did not go to the end of ball sequence. I took off the glass and got the stuck ball out and let it drain. It kicked it back into the shooter lane and we let it drain again and then it went through the end of ball sequence.
For subsequent players, we kept having issues with ball count during multi-balls. A ball would drain during multiball with the ball save lit, but it wouldn't kick another ball into the shooter lane. We would manually kick out a second ball to continue play. This was happening for both Frankenstein and Crypt multiball. For one player during a Frankenstein multiball, he drained one of the balls and ball save was not lit, but it stayed in the Frankenstein mode. We didn't think it would be fair to let the player continue in a multiball mode with only one ball in play, so we ended up taking the game out for the remainder of league.
It seems there is an issue with ball count when a ball get stuck or the game goes into a ball search mode. After league, we turned it back on to play for fun and didn't have any issues.