Amazon MWS連携エラー



I have been using Order & Inventory Management System to manage my Amazon account, suddenly on 2021-12-7 the system lost connection with Amazon. I asked my service provider and received their report as below.

[AccessDenied] We cannot process this request because your account is still being setup or there is an issue with the account. Please log in to Seller Central for more details.

I asked Amazon technical support but replied there were no particular problems with my account.
But I checked there were an article about similar problem of my issue.

Seems that the problem was related to new registered seller with credit card verification issue.
But it also happened on existing seller account.

I have been trying hard to fix this but still cannot find a way out. Any brothers can help?