Folks,
My guess is that you turned it on while the exhaust duct going in to the filter wasn’t connected to the filter? I may have done this at one point and it vacuumed dust up from the dust bin and shot it out all over the woodworking area. 
yep, we did not have the exhaust duct connected to the filter…but in this case it was all the built-up dust in the ducting system being blown out since there was finally a strong airflow. I got a nice sawdust shower :b
On the plus side, the vacuum system is providing more suckage now!