Unfortunately, it appears that the "invis" attribute for edges conflicts a bit with the "concentrate" attribute for graphs.
I have enclosed two images. In the first, everything is visible. In the second, most nodes and edges have become invisible. Note, however, that the first part of the concentrated set of edges from OCS is invisible.
This seems to be due to the fact that the edge from OCS
to DAB is invisible. But, since the other edges from
OCS are visible, I think they should be visible along
their entire lengths (including the portion shared with
the "OCS->DAB" edge).
Input file: b470.dot
Output file: b470.gif