I released version 2.6.1 as a regular SlideMagic app update, which includes the new focal cropping image rendering engine. I have been testing it extensively over the past few days and things are working smoothly.
If you are working on slide decks that you made a long time ago with SlideMagic, briefly check whether the image positioning is exactly as you intended it to be. (Including a possible logo image at the bottom right of the slide). An image that you thought was cropped “fill” or “fit” might just show a tiny gap around the borders. Hitting “fit” or “fill” again should solve the problem.