What about 'Choose a country of residence' registration step? Did you lie about your residency, destriero? If thats the case - you are breaching terms of conditions and should immediately request to close your account.
We expect that a person on the other side of the screen has a common sense, reads english and is truthful.
And talking about IP addresses , four things to mention:
1) One could be travelling in US, without being a US resident. Why blocking the service then? It could potentially lead to inability to close the position or amend the order for someone who is on vacation trip to Miami.
2) IP address blocking can be easily bypassed while using VPN so it doesn't really help. (If you do a little of research you will see how many threads and topics about "bypassing IP blocking".)
3) Many use US VPN services while being located in other countries (to protect their identity and privacy while browsing the web)
4) Many use a remote desktop for one reason or another (which can be also located in US) while a person himself is located in any other countries.
That is the reason why we do request all potential users to confirm their residency before entering the platform, and if you are providing wrongful information, it's not the platform to blame. Restricted country list is also stated multiple times in risk disclaimers, legal terms etc.
We live in a world with 190+ countries. There are many things restricted going from one country or the other. Therefore, users should be aware about their local regulations more than service providers.
Try to mention to your account manager that you are a US resident and lets see what will happen

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Hope this explains, destriero.