I'm going to post this as a clearly titled bug rather than allude to any other issues regarding sweeping. I couldn't find this specifically posted as a bug already.
Sweep is missing from the prioritize overlay. Painting a priority over it with a priority value doesn't change the priority while in this overlay. Painting over it with the sweep operation at another sweep priority changes the priority.
Painting a priority over a sweep operation doesn't function in the priorities overlay. ( see issue description )