Lots of movement to none at all?

[-chook-]

This is my first time incubating eggs. We are on Day 19 (exactly to the hour) of incubation. My eggs were shaking/rocking, specifically a couple out of the total 9 eggs. This happened on day 17 and 18. But today? Nothing. Not a single shake. I’ve looked and stared at the incubator all day. Did something happen to them? Thanks!