Why does iOS swift segue stop working when changing development computer?

I'm building a multiple view iOS app using Swift and Xcode.

I've defined a segue by control-dragging from a button in one view to the new view.

Everything works on the first Mac. When I check in the code, and try to run it on another computer, the button stops working. It displays a black screen instead inside the simulator.

If I redo the control-drag on the second machine, then it works there, but breaks on the first.

I can see that Main.storyboard changes between the two systems. Specifically, the it's the ID in:

< segue destination="xx-yy-zzz" kind="show" id="1234" />

What is the right way to make this segue work?