When moving things around, I discovered that version 11.5 does not "see" changes in the filesystem that happen "under the covers".
I was moving the catalog and members to the disk media sets with ssh and terminal. When I wen to the console to "locate" these media sets, I got errors (strange ones). When I restarted the console, all the icons on the media sets came up red (as expected)
Before restarting the console, they still showed green, and did not seem to "see" that the files had all been moved.