Image Size Glitches

Hi,

I've been working on a project for several weeks, but of course the day I finish is the day everything goes haywire. I'm making a slideshow, and for some reason the images keep changing size. Before they were a consistent size, but now they'll appear extremely small and revert back to their original state only if I pause the video. In the case of one image, it'll suddenly glitch to a large size, even though the scaling is set. It makes it difficult to tell whether I need to adjust the size of the photo or not.

And yes, it does not have to do with scaling. The effect controls read the size the image should be, not what I'm seeing. If anyone has any ideas on how to troubleshoot this, it would be greatly appreciated. I'll gladly answer any questions if necessary. Thank you!