The Runner docs say:

Matter.Runner.[stop](https://brm.io/matter-js/docs/classes/Runner.html#method_stop)(runner)
Ends execution of Runner.run on the given runner, by canceling the animation frame request event loop. If you wish to only temporarily pause the engine, see engine.enabled instead.

I might be missing something, but I believe engine.enabled is a typo and should be runner.enabled. See runnable exampe of pausing/resuming the runner with runner.enabled, and add console.log(engine.enabled) to see that it's undefined.