particles becomes sticky

Hi,
I have a problem with multisphere particles simulation.
when i use same case for simple spherical particles mixing, my results are good but when i used multisphere particles ( 2 or more sphere clumped together to form particle) then particles becomes cohesive and no mixing occurs between particles. i created multisphere particles according to code given in following link
https://www.cfdem.com/media/DEM/docu/fix_particletemplate_multisphere.html

Following is sample code for the multi sphere with three spheres forming a rod like a shape. kindly tell me why particles become cohesive.

atom_style sphere
atom_modify map array
boundary f f f
newton off

communicate single vel yes

units si

region cyl cylinder z 0. 0. 0.075 0. 0.320 units box
create_box 2 cyl

neighbor 0.003 bin
neigh_modify delay 0

#Material properties required for new pair styles

fix m1 all property/global youngsModulus peratomtype 5.e6 5.e6
fix m2 all property/global poissonsRatio peratomtype 0.45 0.45
fix m3 all property/global coefficientRestitution peratomtypepair 2 0.95 0.95 0.95 0.95
fix m4 all property/global coefficientFriction peratomtypepair 2 0.05 0.05 0.05 0.05
fix m5 all property/global coefficientRollingFriction peratomtypepair 2 0.01 0. 0. 0.

#New pair style
pair_style gran model hertz tangential history #Hertzian without cohesion
pair_coeff * *
#physical characteristics of particles:

fix pts1 all particletemplate/multisphere 123457 atom_type 1 density constant 2456 nspheres 3 ntry 1000000 &
spheres 0. 0. 0. 0.0015 0.0015 0. 0. 0.0015 0.003 0. 0. 0.0015 type 1
fix pdd1 all particledistribution/discrete 15485863 1 pts1 1.0

fix pts2 all particletemplate/multisphere 123457 atom_type 2 density constant 2456 nspheres 3 ntry 1000000 &
spheres 0. 0. 0. 0.0015 0.0015 0. 0. 0.0015 0.003 0. 0. 0.0015 type 2
fix pdd2 all particledistribution/discrete 15485867 1 pts2 1.0

#import mesh from cad:
fix zwalls1 all wall/gran model hertz tangential history primitive type 1 zplane 0.020
fix zwalls2 all wall/gran model hertz tangential history primitive type 1 zplane 0.33
fix cylwalls all wall/gran model hertz tangential history primitive type 1 zcylinder 0.072 0. 0.

# Import mesh
fix cad2 all mesh/surface file meshes/impeller.stl type 1 curvature 1e-5

# Imported mesh as granular wall:
fix mixer all wall/gran model hertz tangential history mesh n_meshes 1 meshes cad2

#integrator

fix integrate all multisphere

#gravity

fix gravi all gravity 9.81 vector 0.0 0.0 -1.0

#Timestep
timestep 0.00001

#Area where the particle are introduced from is set:

region factory cylinder z 0. 0. 0.068 0. 0.3 units box

#

#thermo setting
compute 1 all erotate/sphere
fix ts all check/timestep/gran 1000 0.1 0.1
thermo_style custom step atoms ke c_1 f_ts[1] f_ts[2] vol
thermo 1000
thermo_modify lost ignore norm no

#insert the first particles so that dump is not empty
#fix ctg all check/timestep/gran 1 0.01 0.01
#run 1
#unfix ctg

#defines how the insertion is going to be done:
#particle insertion-large particles
fix ins1 all insert/rate/region seed 67867967 distributiontemplate pdd1 &
nparticles 4000 particlerate 10000 insert_every 1000 &
overlapcheck yes vel constant 0. 0. -2.0 region factory ntry_mc 10000

run 90000
unfix ins1

#particle insertion small particles
fix ins2 all insert/rate/region seed 67867979 distributiontemplate pdd2 &
nparticles 4000 particlerate 10000 insert_every 1000 &
overlapcheck yes vel constant 0. 0. -2.0 region factory ntry_mc 10000

run 90000
unfix ins2

#make a dump of particles and the stl file
dump dmp all custom/vtk 200 post1/multi_*.vtk id type mol x y z vx vy vz fx fy fz omegax omegay omegaz radius
dump dumpstl all mesh/gran/VTK 200 post1/mesh_*.vtk stress wear cad2

run 10000

#rotate central shaft
fix movecad2 all move/mesh mesh cad2 rotate origin 0. 0. 0. axis 0. 0. 1. period -2

#run 5 seconds
run 1200000
unfix movecad2
run 100000

can any one help me why particles become cohesive as i am not using any command or property that give cohesiveness to particles.
thanks in advance