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. Before I release it, I will make sure that everything is working properly and then I will release it.
That's a strong gradient indeed, any lights in the neighborhood? And are you using calibration files?
Apart from that, in APP there is a tool to reduce gradients. If you have your final image, you can go to tab 9, tools and do light pollution correction. Place a few small squares (like 3) close to the bottom, spread out. Then another 2 left and right from the object in the middle. And then 2 close to the top on the left and right. Click "calculate" and check what happens.
@vincent-mod Light Pollution Correction didnt really help Results of that are below, if anything made it worse. As for light pollution and calibration files. i was in the middle of a field (bortle class 4) with not ambient light sources around and i used Darks, Flats, and Bais frames (30 each). I processed the same way i have my other images, never gotten a gradient like this before and have no clue why.
Ah excellent, yes a flat that has an issue (or any other calibration data) causes issues like this indeed.

