This is a lengthy explanation. Summary: you have to comply with each and every region’s requirements before you will be reinstated.
Explanation: I had the same problem since January, 2020. You are likely suspended because you have not finished the registration documents for specific markets. Each region requires different - or possibly duplicate - information from you. Just sending it in for the amazon.com USA market does not mean that it has been transferred to the Global sites. That’s the rub. You have to toggle down on the various seller accounts that you have, open that market (ie amazon.jp) , and then go to Performance Notifications. There, you will go to see your performance notifications for each of the countries or market areas, and you should be able to see which ones are missing documents. Then, submit the documents through their appeal button.
When I signed up for Amazon seller accounts, I just checked the global accounts, erroneously thinking that I could just open these up contemporaneously and without issue. The problem created by this is that there is no mention in any emails submitted by Amazon.com that the suspension is related to the global accounts being the related accounts, and not some other account. I was suspended immediately for “related accounts” and no one from Amazon would tell me what related accounts meant. That was the biggest reason for the issue. The first person I spoke with suggested that I had other amazon.com seller accounts that I did not disclose. Then, another said that it could have been due to others having the same office address as I have. Thus, I spent time trying to demonstrate never opened up and account, and that if there were accounts they would have been from others with the same office address.
It took four months and a helpful rep to finally explain it was the global account issue, and that I had to look and see what documentation each and every global account requires.
Please note that there is another catch. You cannot just close the global accounts in order to become compliant and have your amazon.com account opened. You need to individually comply with each account’s requirements and submit that documentation; get an active account; and then close the account (if that’s what you want to do). You must submit this through the Appeal button, not through another method. As an aside, I was able to close all of the European accounts the same day I submitted the information, but I have had to submit my information to Japan (I am on my third submission of the same documents).
I realize that this is a lengthy response, but I am attempting to provide some detailed guidance so that others may be able to save themselves some time and frustration.
Bottom line: You must comply with each regions’ requirements, submit everything through the “appeal button”, which is at the end of the performance notification for a region, and then once you have ben reinstated for a region, appeal again, and you should be reinstated.