I imported from CSV file. I tried importing from a feature service, it still didn't work. With a help from ESRI support, I was able to import GCPs as GCS WGS 1984 rather than State Plane. This worked for one project. I've tried the same setting with another project. It didn't work. Drone2Map was able to generate 1 m contours only. I would like to have 1 ft contours. So far, Drone2Map was able to generate 1 ft contours without importing GCPs.