Sorry for the slow reply. Do other nuts and seeds cause digestive issues when soaked overnight and/ or toasted and/ or ground?
I ask because there is thousands of years of history of processing certain nuts or seeds, I have heard experts say this is to make them more digestible particularly for children. For example the archaelogical record shows hazelnuts have been bulk harvested (Europe) and linseeds have been farmed (Middle East) since the stone age.
The only documentary I can name is the fascinating ‘Wild Food’ series with Ray Mears and paleoethno botanist Gordon Hillman (on Youtube). It is pretty old so do watch more recent archaeology articles and documentaries.