I have no problems either changing the Custom sort order of photos in the Saved Slideshow. The problem is in the step before because in creating the Saved Slideshow the sort order of the chosen Collection is no longer retained and photos are imported/used sorted by Capture Date. So, suppose I have some hundreds of photos in the Collection, I should now change them manually in the Saved Slideshow to recreate the Custom sort order of the Collection; this would be an unnecessary duplication of efforts, boring and time wasting, a non-sense. I hoped there was a flag somewhere to avoid this but have found nothing so far, not even in the Preferences... Thank you for your attention and support.
Hello,
I think I get your problem, as I came across this issue recently. So, in the Library view, go to your Saved Slideshow in your Collections, go to Grid view and at the bottom, change the sort order to 'Custom Order'. It seems to default to 'Capture Time'. If you select ' Custom Order', the order you created in the Slideshow module, will be retained!
Make sense?