This issue can no longer be reproduced with ArcGIS Excalibur in ArcGIS Enterprise 11.5. Ensure that the input images in the Detect Change tool are overlapping imagery and are different images. Adjust the threshold for more or less results as well. For more information, please see the Detect Change tool documentation: https://doc.arcgis.com/en/excalibur/latest/get-started/comparison-tools.htm#:~:text=of%20the%20tool.-,Use%20the%20Detect%20Change%20tool,-The%20Detect%20Change