we have a couple of issues running the latest version of your plugin on 3.5.1 and 3.6. The issue is the following: We installed the plugin, we can successfully create a new slideshow and add slides to it. After pressing "update" or "publish" we stay on the slide-show page and create a new page that uses the slideshow in a new tab. Everything works fine and displays correctly. After we navigate away from the slideshow page and come back to edit the slide show, no slides are shown anymore. At that point in time also the page that has the slide-show embedded does not render the slides anymore.
After some debugging we found that the method getSlides seems to report an array of some complex properties when everything is ok, but once we observe the issue, an array of the correct size is returned, but each element is a string that says "ARRAY".
The usage manual says that we shoudn't forget to "save" the slideshow. We have no clue what you mean by "save" as we only have a publish/update button.