Images within InDesign file getting corrupted
I'm new with Adobe CC. Recently, I inserted (Ctrl + D) about 40 illustrations into an InDesign file. When I opened the same file a few days later, I found two illustrations pixelated (or corrupted). One heavily, another mildly. I wonder what might be the reason. It's been an unwanted hassle replacing these illustrations. Below is a image before and after the corruption:


