Hi Martin.
I can’t see anything obvious wrong with the FITS header, I don’t think HOPS has specific metadata dependencies.
Is the target in the HOPS database and are the target parameters auto loading at run time or are you manually entering the parameters for a new target previously unknown to HOPS?
Assuming the target parameters are loading/loaded correctly, try skipping the calibration frames and just run with a small set of the data frames, perhaps the data frames are being compromised during calibration, if so, running an uncalibrated set would show if that is the problem.
If HOPS still fails to solve, even when uncalibrated frames are used, upload a small set of frames to a file share service (Dropbox, Google Drive, One Drive, etc) and post a share link back here and I can try running them on the mac version of HOPS.
Two of each calibration frames and half a dozen good quality, random, data frames plus the target coordinates and target name would be enough to test.
William.