Objects destroyed / disappear outside game window

I'm trying out the free version of 2.5 before I upgrade from 2.0, but in my test game, I'm experiencing a weird issue.

I create a ground via a loop, whereby on each loop an object is pasted into the background as a platform, with a frame size larger than the game window size - the game scrolls. However, when the game window begins to scroll, I see that the ground objects either aren't there or have actually been cut short beyond the boundaries of the window size.

Attached is a screenshot to show the problem. Any ideas?
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My platform needs to be a curved hillside, which is randomly generated at the start of the frame such that no two games are the same. I'm happy with that part of it, but what I don't understand is why objects are being chopped off if they were inside the frame but outside the initial game window area. I've never seen that in MMF before. Does anyone know why that would be happening in Fusion 2.5? Could it be a bug with the free version?