I'm not certain why it didn't work. It should, but it seems to me that Wrap has a problem dealing with more than one instance when they leave the layout. Just guessing :/
My hack involved setting the Origin to the far left, then checking when the cloud reached the far right, and resetting it's x-position to '0-cloud.width' so it starts again. That's all I meant by boundary check. The boundary at the far right of the screen.
I don't think this is a good enough solution, but at least it works :)
If your vision so exceeds your ability, then look to something closer.