Also note that you have defined a particle size distribution but you are not using it - the definition is here, in the DEM pane:
but you must select it in the IC pane:
I noticed this because I set up monitors for max & min particle size and this showed me that the particles were all the same size:
I also suggest decreasing the VTK write interval - if you only write a frame once per second you’re not going to see much activity. I set it to 0.001.