I think I have discovered a bug on Enterprise Sites, but I'm not sure if this is specific to our deployment.
When I preview a Map Image Layer service in the Preview Map (https://enterprise.arcgis.com/en/sites/10.9/sites/use-the-preview-map.htm), the service displays the correct extent, however when I navigate to another page and then view the same MIL (or any other MIL), the extent pans to 0, 0 lat/long.
Hosted Feature Layers display correctly and do not have the same problem.
Is anyone else able to replicate this issue?