After having installed emojis support, the Whatsapp notifications display emojis. Not a big deal, but better than question marks.
The problem is, those notifications disappear without being ignored or answered. If you select it, it's displayed for a few seconds and then... gone.
It remains in Android notifications, at least.
Also if you scroll the notifications list in the watch widget, there are no emojis, just question marks.
KIndly pass this to dev team