When auto-downloading the ephemeris and alternate navigation files, the alternate navigation file does not cover the same time period as the flight. This usually occurs soon after the flight, when the alternate navigation file has not been updated on the FTP site where this file is downloaded. It can also happen when the flight occurs across two GPS days (ex. January 10 @ 23:50 to January 11 @ 00:10).
Probable Solution #1:
Delete the file path in the alternate navigation field and process without it. In most cases, Loki produces it’s own navigation file so the alternate file is not needed unless you encounter the error “Rover Position File (.pos) is Empty“