When links are in an inaccessible CC Library, instead of "Missing" (red dot in status column) the links are "Waiting" (stopwatch icon in status column).
This also causes repeated errors "This file is already open by another user or another application. This file may be stored on a network server and cannot be opened until the user closes it."
So far, the only path forward is to repeatedly dismiss the error and try to relink the artwork before the error re-appears. This has to be done for each "missing" link.