Swipe action not working consistently on iOS

I’m using a very basic scroll method on an iOS native app (using the emulator). My code looks as follows:

	TouchAction swipe = new TouchAction(driver).press(30, 600)
			.waitAction(Duration.ofSeconds(3))
			.moveTo(30, moveDown)
			.release();
	swipe.perform();

The issue I’m experiencing is that it deosn’t scroll to the same place each time. The first time it will scroll to a certain point, but then when I run the exact same test again, it scrolls to a different position.
Has anyone else experienced this?