Diffusion flux along cos I of the 3D FP equation in (J_r, L, cos I), for J_r​ = ​0.1 and cos I​ = ​0.2, as a function of L and for various smooth functions g_a (equation K.2). Here, we consider an isotropic cluster with rotation parameter α​ = ​0.25. For any smooth g_a, the flux diverges like 1/L for L​ → ​0. As a​ → ​∞, that is, as g_a tends to the sgn function, the flux converges to the LBD flux pointwise, which exhibits no divergence.