You can download previous versions of Skyline by going to the "Unplugged" installer page, and then clicking on the "Archive" link:
https://skyline.ms/wiki/home/software/Skyline/page.view?name=install-64-disconnected_20_1

It would be very helpful if you could send us your Skyline document and raw files so that we can figure out what is going wrong.
In Skyline, you can use the menu item:
File > Share
to create a .zip file containing your Skyline document and supporting files including extracted chromaotograms.

Files which are less than 50MB can be attached to this support request.

Your raw files will probably be larger than that, so you can upload them here:
https://skyline.ms/files.url

-- Nick

I will note, however, that until you have actually verified that 19.1 asked to do exactly the same thing works as expected, this may still be a settings issue that you are misattributing to a version change. This happens a lot. People remember something working in a prior version and jump to the conclusion that the change is a version issue when something else has actually changed that is causing the problem.

But having you try the same thing with an older version and getting your files will help us understand better. Also, it always helps to get screenshots of the problem you are seeing and what you are expecting.

Thanks for posting to the Skyline support board.

--Brendan