Automatic start/end
Leave start and end unset, and Ember tucks them next to the neighboring shape of the same color.
Automatically setting start and end is a new feature, and it's on for new projects by default. You can turn it off in your project settings. A project you saved before this update leaves it off until you flip the switch.
If a fill or outline doesn't have a start point yet, Ember drops one at the closest spot on the previous shape of the same color. An unset end does the same with the next shape of that color. A different color, or no neighbor, keeps the usual start and end. Anything you place yourself stays put. These points are figured out as the design sews, so they aren't saved as points you placed.