I played with Ekos & Stellar solver and it all worked for me in simulation. Thanks for the work.
I have a few remarks about using ASTAP (as a backup solver) in the menu.
1) The extractor can be activated using the ASTAP option. It doesn't do anything useful for the local ASTAP solver. So I would suggest to inhibit the options if ASTAP is selected or force the correct "source extraction method"="Build in method for solver" .
3) It seems not possible to adjust the search radius. This is fixed at 15 degrees. I would suggest to make it adjustable.
4) The be sure that the best down-sampling is taken, I would suggest to add in the command-line "-z 0" to force auto selection of the down-sampling
5) Warnings and errors of ASTAP seems not being processed. Warning are in the .wcs file as warning= keyword. Errors and warning are in the .ini output file behind the warning ='' and error ='' keywords. Or alternatively just report the full log with warnings and errors included
See www.hnsky.org/astap.htm#astap_command_line