Yes, the png issue is fixed (master branch, compiled on Linux)
About the tiff file: is not only this image. I’ve stacked multiple videos of the same session and all are broken, I can’t save any tiff file from those stacks. Before beta2 I was using the same stacker (PlanetarySystemStacker).
Also I’ve tried with other monochrome images, not produced by me, created with a complete different software and I’ve obtained also a wrong tiff export (small file, all black)
(btw, thanks for your comments about this little Mars)