In the normal workspace called "workspace", I searched for "Copy of ..."
and found a folder with that name under:
workspace/.metadata/.plugins/org.eclipse.core.resources/.projects .
I figured that might explain why it "filtered out" that project when I
tried to import it from the temporary workspace.
So I deleted the folder, restarted eclipse with "workspace" and did a
refresh. Eclipse recognized the project "Copy of ..." was missing files,
and asked if I should delete from workspace. I said yes.
I restarted Eclipse into "workspace" and tried the import again of the
project named "Copy of ..." from the temporary workspace. This time it
listed the project and let me select it and do the import. Afterwards,
however, the project refuses to show up in the Package Explorer -- the
original problem I was having. I tried the import in both modes --
linking into the workspace and copying into the workspace; did a refresh.
Still refuses to show in the package explorer. Yet I have no problem
importing the same project into my new "workspace2" workspace.
There seems to be some deep corruption in this workspace / project
combination that is very difficult to root out.