Not sure about the Windsport configuration for the tail lights. If both lights on each side perform the same functions then more than likely it is a switch problem. If, however, one light on each side is used for brake lights while the other is turn signals it could be a wiring issue.
Did the brake lights work during the PDI? If so it could be a loose wire or ground connection.
Don't waste your time going to a Ford dealer since they did not install the lights they will more than likely tell you it is a Thor issue unless the problem can be tracked back to the switch or Ford installed F53 light wiring harness.
US Army (Ret)
2020 Entegra Accolade 37TS
2019 Jeep Grand Cherokee Trailhawk (Toad)
FMCA - F432054