Send a copy of a file to tinderbox@eastgate.com, or post it here. There might be a problem!
The most likely explanation is that you’re looking inside a note that has no children. The breadcrumb bar above the map view will tell you the ancestors of the current view.
curious though that once I fixed it in one file, all the other files were showing top level Map view. possibly something got set in the app that affected view in all files? Running 9.1