I regularly work with on an .mxd with multiple data frames, showing updates on one Area of Interest shapefile per data frame. This has always worked without a hitch to show updates on 2, 3, or 4 non-contiguous extents side-by-side.
Recently, I added a data frame/AOI that is contiguous to an existing one, but I still want to show them on individual data frames to provide discrete updates. Without me doing anything, I find the shapefile from one unique data frame also showing up in the adjacent data frame. When I toggle off visibility of the shapefile in the neighbor's data frame, after a click or two, it also turns off in it's native data frame. If I "remove" the alien shapefile from it's neighbor's data frame, I get a red flag error that the file is now missing in the native data frame.
Any ideas on a workaround here?