When using Region checkpoint, sometimes the difference can be subtle and difficult to identify.
It would be helpful to either be provided with the area that fails, or the difference highlighted, or...
Already present. When you view the picture in the log, you can see a side by side comparison of actual versus expected and toggle from the provided toolbar to highlight those differences. See https://support.smartbear.com/testcomplete/docs/testing-with/log/viewing/pages/generic/picture.html