whitespace-mode does not display hidden characters in a patch file

Question

I have a patch file on which if I do cat -A , I get :

  if (zif->rtadv.AdvIntervalOption)$
    {$
      struct nd_opt_adv_interval *ndopt_adv = $
^I(struct nd_opt_adv_interval *)(buf + len);$

But on emacs with whitespace-mode enabled I do not see any of the hidden characters:

Why?

I do not know what controls this behavior, and whitespace mode works fine in fundamental & c buffers.

Here is my whitespace display mappings:

'((space-mark 32
              [183]
              [46])
  (space-mark 160
              [164]
              [95])
  (newline-mark 10
                [36 10])
  (tab-mark 9
            [187 9]
            [92 9]))