No official makeup date has been announced, though the fight card will continue without the light heavyweight bout.
Saint Preux's management company, Knock Out Representation, tweeted the fight will be rebooked for September 5, but the UFC hasn't confirmed.
Though he is not showing symptoms, Knock Out Representation said the 37-year-old was previously infected with COVID-19 and tested both positive and negative this week.
St. Preux (24-14, 11 KOs) has lost four of his last six bouts, dating back to February 2018. He most recently suffered a split-decision defeat against Ben Rothwell in his heavyweight debut at UFC Fight Night: Smith vs. Teixeira in May.
Saturday presented an opportunity to get back on track against the 32-year-old Menifield (9-1, 8 KOs), following his first career loss in June, which came via a unanimous decision in favor of Devin Clark.
The two will have to wait at least a few weeks before facing off in the Octagon.
UFC Fight Night: Munhoz vs. Edgar will kick off with the preliminary card at 6:30 p.m. ET on ESPN+, followed by the main card at 8:30 p.m. ET.