Last quest i needed to finish challenge. Was not finding it on sw section, found it at Aso settlement on board in town
All main and side missions, including many locations where they start are readily available in GZ Wiki,
link: https://generation-zero.fandom.com/wiki/Missions
Note: don’t check it if you don’t want spoilers.
Few months ago borders between Farmlands and South Coast were changed. Before that the point that you found the mission belonged to S.C.