Particles are invisible in houdini and it happens in both 18,5 and 19, no matter the size they will stay as little white dots that you can see, regardless of the setting "Display particles as" (Points, Discs, Spheres, nothing changes the particles.)
I also tried tweaking the settings in 123.cmd in the scripts folder to no avail.
It is using the Vellum Solver with Grains constraint
