UPDATE FROM MABULA
I have had a very rough 2 months unfortunately health wise. I was struck 3x in a row with bacterial infections. The second infection occurred  after a routine hospital checkup and I became very sick. I had to rest and take a lot of antibiotics. Once I was recovering and restarting work 1 month ago, I again became sick. The infection was not yet gone, so even more antibiotics and rest was needed. Needless to say, it took a lot of my energy and I needed a lot of rest.
Finally, the infection is really gone and my energy is coming back step-by-step now and I have started work again. I am terribly sorry to have kept you waiting for support. I will address all outstanding questions and e-mails step-by step and will be on the forum daily from today.
APP 2.0.0-beta47 will come soon as well, a lot of work was already completed before I became very ill, so the release is also nearly ready for you. Beta47 will be much faster actually. Many workflows will be more than 2x faster, mosaics can even be 10x faster than before because registration really received a major boost... all compared to beta46. Â Before I release it, I will make sure that everything is working properly and then I will release it.
I am stacking my photos with AstroPixelProcessor last 3 years and process them in StarTools. Today I try stacking Comet in comet mode in APP, save file in fits format but ST was unable to open any fits file from that session, no mather I saved it in 16 or 32 bit version. ST was unable open the file, it says "Could not read file, make sure image file is a fits file, an uncompressed, IBM PC byte order tiff file or a png file".
Saving it in APP to all files, to all bytes, but ST was unable to open those files.
I was trying to open same older files from summer stacking and ST opens them normaly. So, I am alomst sure that is a APP in question. Is there any procedure to save proper file (fits, 32 bit or tiff 16 bit etc....).
Thank you for answer.
Marko
So this happens specifically when saving after comet registration? Or also for regular lights?
Somehow I managed the problem opening fits files. I don t know why, but seems my folder with light and calibration frames was somehow corrupt. I make another folder & move lights & calibration frames into this new folder, problem was solved. I can open now stacked APP fits in StarTools....
Thank you for the replay......
Marko