Is there a way to switch off the dynamic placing/formatting. I have a grid of 12 (4 columns by 3 rows). However, if one of the images is blank (missing) then it seems to auto adjust and screw up the formatting and alignment. I would prefer it just show a blank box and keep the formatting
Container columns and responsive design
When you are in the usual view in the builder, the view is responsive and columns get pushed below one another. To see how your screen will display on different screen sizes, in preview mode (the little triangle), you can drag the borders of the screen to test.
Display of your blank images
In the container options/settings, right hand panel towards the bottom, you should be able to set top and middle-align. By default containers are set to middle-align. Could you try and set it to top-align?