The length (L) of the central region (which is the supercell structure used to create the device) is supposed to be divisible by the length (l) of the spiral primitive cell along the spiral axis, i.e., L= n * l. In your device, this does not hold true, n=5, l=10 Angs, but L= 52 Angs , meaning that you have not constructed your original supercell (used to create the device) correctly. Enclosed you can find the corrected electrode, central region and device structures in 3 python files, as well as a png file with the correct device structure.