Cyclone case having weird anomaly

I am running a cyclone case (files attached). MP-PIC case

It runs fine. However, when the particle flow is visualized in Paraview (For example), we see the particles just come out of the inlet and don’t even do one spiral and suddenly fall down from a certain point in the radius (see figures).

I tried changing the slip velocity factor, the CFL condition (now its 0.1), the mesh is around 270K fluid cells (very fine with dx = dy = dz of 3.5 mm) results in same issue

Inlet conditions (velocity, and solid loading was changed like 2X or 4X or 0.5X ) same issue was appearing.

Me and my team could not find out if something is wrong with the (a) geometry or mesh, (b) the way we have our parameters in PIC; (c) or any other issues.

Thus, was wondering if any help on this can be provided.
Fassani_Cyclone_ver2.STL (29.8 KB)
test_cyclone.mfx (17.0 KB)
geometry.stl (168.4 KB)
geometry_0004.stl (168.4 KB)