bug#64177: outline-minor-mode-highlight fails to activate for custom headings

[uzibalqa]

I have made custom headings for outline-minor-mode 

But

(setq outline-minor-mode-highlight 'override)

does not succeed in displaying the foreground colours at the
defined levels when using

(set-face-foreground "outline-1" "#ff62d4")
(set-face-foreground "outline-2" "#9f80ff")
(set-face-foreground "outline-3" "#fe6060")

Yet, the colours get properly displayed for the default headings
for the specific major mode