This story explains how ballots get “fixed.”

Further slowing down the count, The City’s election workers are required by the state to fill out, or “remake” a new ballot when a San Francisco voter — who is allowed to rank up to three candidates for the same local office — leaves one or more of the slots blank. According to John Arntz, the head of The City’s elections department, ranked-choice voting in San Francisco has always resulted in ballots being kicked out as “undervotes” when three choices are not ranked. But in the past, election workers have visually inspected such ballots and then put them back through the machine.