That might well explain it.
The issue occurs when the three layers within the image don't have the same dimension - so when you zoom right out, one or more of the layers keeps zooming beyond the bounds of the other layers because it has different image dimensions, and so the grids no longer match. The extension code should adjust to this, and for most cases it will. But there are some cases where it can't - and you see the result you did.
To get around this issue, without FG running, remove the image file from the campaign images directory. Re-start FG and make sure the image entry is not in the campaign data list. Then add the image back, and it should create a new clean image record with the correct dimensions across all three layers.

