Correction: You made TWO colliners which worked well:.......I seem to have made one which works well. I've made dozens that didn't. ........
(1) The 6-element Franklin Collinear.
(2) The 24-element Coaxial Collinear.
It seems that since Franklin looks more like a dipole, and less like other collinears, it is often missed out from collinear category.