Simulated pin pushers break when using a signal from a signal producer (I didn't get the glitch when using a belt reader).
As shown in the video, I used blank circles with increasingly many pins below them and the first simulated pin pusher had results that don't match what would be expected, but the rest were normal. With a max height circle in normal mode (--------:--------:--------:CuCuCuCu), connecting that to a simulated pin pusher broke the rendering and the ability to save until I removed the signal producer.
One picture shows that it doesn't just happen with the circle, or even with just a single layer, and that each layer has different effects. And the other picture shows that a belt reader output doesn't do it.