Nexus is in kingdom group 9 instead of 10? When I got the message for which kingdoms were unlocked (“Congratulations, you have unlocked the following kingdoms:”) it did not include Nexus (and yes I have screenshot of that message and I did double check).
If you forwarded them my main account invite code that won’t help much because this happened on my alt.
Zendesk articles still have some outdated information - for example kingdom rewards are definitely wrong on the article I linked because game modes are now unlocked by hero level (+world quest) rather than when you complete kingdom groups.