Trying to figure out if I have a problem with mine, or just buggy software: do you guys frequently have multiball rounds end unexpectedly/jackpots seem to cancel out before shooting the cannon?

Everything works normally with mine, all switches test out going through each in the edges test. I don't think it's just losing track of balls or a normal trough switch issue and thinking I've drained, as the ball doesn't end and I've never had it think I drained improperly in single ball play. But I guess I will recheck those. I also don't think it has ever offered the pity jackpot grace period to load the cannon either when it does this... it's just boom back in single ball gameplay. Several times I've started payback time right in the middle of a multiball, I was thinking that shouldn't be happening.

To follow-up, I think the problem here was the skull VUK/switch falsely triggering when a ball was still in the cannon.

I bought a rebuild kit for the VUK from pinballlife, which comes with a spring to push the cup the ball sits on back up (the bottom of the cup triggers the switch when a ball pushes it down). Mine was either missing the spring or originally didn't come with one, as I had read some indications of. Seemed like the weight of the cup alone would either trigger the switch again, or it would otherwise fail to reset properly without some additional help from the spring.

So far, so good now...