When in the slide show preview screen, click on the Customize button (bottom left). Select the last image and increase the time say with 2 seconds. Then create the slideshow with advanced editing so that the show will become part of the timeline. Then go to the end of the clip where the fading out starts and simply cut off the fading. By extending the duration you still have sufficient time left to show the image.
In some templates there is more customization possible.
If you like the output of the motion template (as you say you use), why not manually set the show by:
- insert the images into the timeline,
- define the duration for each or all images
- go to edit and to Pan & Zoom
- select all images
- select the random motion style and
- click on apply to all.
You can change the results in the timeline manually if you want to.
Have fun