Don't call resetForceAndTorque inside DEM
The DEM solver contains
// Resetting the acting forces
bodyIt->resetForceAndTorque();
[...]
// Resetting the acting forces
bodyIt->resetForceAndTorque();
which I don't think should be there, and it definitely shouldn't reset the force twice. HCSITS does not reset the force itself, that's what ForceTorqueOnBodiesResetter is for.