I fiddled with it a bit more after I posted this, and found the following (once the updates stop working):
- when stopping SL is checked Chaotica will cease the incremental updates and will only update when the stopping SL is reached, even following iterator or coloring changes
- when stopping SL is unchecked Chaotica will update incrementally like we've been used to, so it's probably best to leave this box unchecked while tweaking until you're ready to render your final image
I'm not sure if this is a bug or a change that was made on purpose, but either way it's not a big deal as long as the incremental updates work one way or another.