> There’s a variety of fraud, tax and money laundering scenarios that probably flagged the OP as a risk.

You are absolutely right. Moreover, if someone is flagged as such a risk, it is illegal for anyone from the bank to tell that person that they've been flagged. So the OP will never find out exactly why they've been locked out. It's unfortunate, but Marcus is small, and they don't have the experience with customer service as well as experience with various types of fraud that a bank like Chase or Wells Fargo has. I guess that's the downside that partly explains their higher savings rates.

> If you’re emigrating from the United States, you should probably find and use a bank that has a business model that caters to that scenario.

And generally try to be proactive- talk to them before you do anything, understand what is needed, provide supporting document and try to get things pre-approved as much as possible.