I have a presentation with 15 images and accompanying text which works correctly. I can reorder and select which layer the images appear without issue.
I would guess that you are not setting the correct layer for the third image.
What to try is move the images in an overlapping stack and watch how they move up and down the stack as you use the forward and backward button.
Once in the correct layer, re-position to the correct position.
shape 3 is in the wrong layer: shape 3 in the correct layer: