Black line when changing focal point within cropping tool

Here's a video to show my issue. I'm using an image placeholder in Slide Masters rather than cropping an image I've added. So, I'm clicking to add a file and it crops it to the size of the placeholder. Then the only way to change the focal point (that I know of) is opening the crop tool and moving the image around. I want to keep the placement of the image and crop size the same. But it's super hard not to accidentally move it a sliver up or down when the image height is the same size as the crop box. You can't see anything wrong after saving the new crop, but it shows when previewing the slide. I exaggerated in the video just to show what's going on. I know it looks silly that I left a gap, but that was just to show the black line better. Most often, I can't see any gap, but I'm still getting the line because it moved like a pixel off from the top or bottom of the crop box. I'm wondering if there's a way to make sure it stays the same on top and bottom but just move it left and right. I have other developers that are likely going to get a line each time otherwise.