Vacuum suction

Does anyone have issues with the vacuum not sucking out the holding tank of dry debri?  The dust bag is not full and the machine holds the dust in the holding tank on the robot instead of sucking it out when it returns to base.  It goes there the emptying phase and you can  hear the machine attempt to vacuum out the holding tank but when i check it,  the holding tank is always clogged.

Yes, I’ve taken it apart and found that it is collecting in the vac itself; not suctioning to the collection bag. The vacuum has detected a full bag and / or a backup in the suction line. I’ve purchased more bags (reusable dust bags  from Amazon). They come in tomorrow. Then I will see if there is a clog in the line.  Hope this helps!