Mindstorms, black orphaned data wires I've just copied a loop element, which had a data wire going into it.

The internal wires (from the old external data wire) are now black, and I cannot delete them, or re-link them to a new external data wire.

They just don't seem to be selectable any more.

Can anybody give me an clues how I can do anything with them?
It looks like you have discovered a bug. You should report it using Help > Give Feedback.

For working around the problem, the only thing I know to do is to cut the blocks with the black wires and then paste them back in. This seems to get rid of the black wires.