When i process a stacked photo the changes are not saved when i export it to TIFF or JPEG.
Using Siril 0.99.8 on windows 10, photo’s stacked using sequator. Exported TIFF is opend in Capture One 12.
Both the TIFF and the JPEG looks similar to the preprocessed photo.
We have new tutorials in English that will help you, this one in particular: Siril - Tutorial for a complete processing of astronomical images with Siril and its scripts
I’m not sure I understand your problem with so few details, probably you haven’t stretched the histogram.