I noticed that several custom team logos, including downloaded (and unmodified) ones from others' sites, were not displaying correctly in my leagues (monochrome, horizontally compressed, off-centered, etc.). After much experimentation, I discovered that the logos that were experiencing this condition were in indexed color mode exclusively (in Photoshop). After changing them to RGB mode and saving them, then restarting OOTP, they displayed correctly.
Anybody else seeing this?