Tyndall effect looks to be a multiple scatter effect where light scattered from more than one point in the suspension. The Rayleigh formula is for single scattering.
I actually did a masters thesis on multiple scattering.
"Light-scattering measurements from dense optical systems" P. C. Colby, L. M. Narducci, V. Bluemel, and J. Baer. Phys Rev A Vol. 12, Num 1, Oct 1972 pages 1530-1538.