I upgraded to 4.0.6 Jul 22, 2023 version of Story today (I might have missed a prior update or two), but noticed that newly generated slideshows have a blank slide at the end when swiping thru the photos. In my case, I have captions and when I swipe past the final photo it appears as a black screen with the caption of the prior slide (i.e., the final slide). I regenerated an older slideshow and it produced the same result.

It only happens when swiping. If I used the arrow buttons on a laptop, the problem doesn't happen.

I had to change recently how the last image is handled after the last one, and it seems I forgot to recenter the image when the "After last" action is "Do nothing" or there's no sibling folder you can move to in case of "Next folder". I will fix this.