particles size parameter doesn't work

I tried adding particle in my model and wanted to reduce the size of the particle. but the particle.setMin/MaxSize() doesn't work. neither does the "size" field that is read in the model.json when you declare you particule. also reducing the size of the bone it is link to doesn't impact the size of the particule.

i also feel like the angle field do nothing.

also if you put the density of the particule to 0 (in model.json or thought particule.setDensity() ) and then make it positive to activate the particule, the first time, a lot of particule are spawn at the same time.