I think your wires get stripped out by the compiler because they are dead code. (With my idea implemented, we would immediately notice and not try to put probes on them. ;))
I think it is not a bug and the probe reports correctly that nothing happens with that wire during execution, because it would make no difference in the end anyway.
Of course it would be nice if a probe would indicate that fact in some way, e.g. instead of saying "not executed" it could say someting else, indicating that the code got stripped out and does not exist, because it is irrelevant for the outcome.