Strange.
I think there are still 2 possibilities.
In settings > email + accounts > tap the account and check what you have under "Download new content" . If it is "daily" that may explain why you do not see the contact after you added them in outlook because it only gets new content daily.
If so change it to more often or just in "emails + accounts" tap and hold the account and then sync.
Or the contacts you add have no phone numbers and in the people hub at the top under "PEOPLE" under "contacts" you see "showing" and there should be "all". If not tap it and change to all.
If it shows "contacts with phone numbers" it does not show contacts with for example only a email.
In your HTC 8x can you copy contacts to SIM and then import them via your SIM on your 630