I found this question with the same problem I'm running into.
Unfortunately I didn't found an answer to this and couldn't aks in the original post. Maybe someone can help me my code looks like:
img = File.expand_path(Rails.root+'app/assets/images/scb_footer_logo.png')
sheet.add_image(:image_src => img) do |image|
image.start_at 6,6
image.end_at 6,6
end
It seems to me it would ignore the start_at because it always starts at A1.