If more than a tiny amount of dust is reaching your vacuum/dust collector or if material is swirling in the cyclone without dropping into the dust container, this indicates that there is an air leak in your setup.
Make sure the lid of the dust drum is in place and well seated.
Check for any damage to the foam seal of the lid.
Ensure the drum lid clamp is tight.
Check for holes or leaks in the dust drum.
Check for leaks along the flange of the cyclone.
Check for leaks on the outlet's shoulder connection.
In addition, large, bulkier material might swirl. Restart or temporarily cut off air flow to drop material down.
