Do the following and check your address history again.
- Login through PC
- Update your app
If the particular address is still not there, I can only think of two reasons:
1. A glitch on their side (I tested their app, Its buggy as hell)
2. Malware on your side (There is a virus called copy paste although I'm not sure if it's also applicable in phones)
Either way, Only the coinbase team can clear this up and since you've already submitted a support ticked, you can only wait now.
Lastly, Under what category did you placed it to?, because according to coinbase only the following will be prioritized: and others will obviously have a delayed response.
Our team is prioritizing only trust and safety, account lockout, and delayed payment issues. Specifically:
Account compromises
Account lockouts (password resets, 2-factor authentication, device verification, lost access to email address)
Delayed payments or orders
We are unable to prioritize other issue types at this time.
But I think your problem can also fit into "Account Compromises" category although just a potential type since nothing is concrete yet.