Hello, my suggestion is that you check that "trusted access" for SSO is enabled in the organization, please go to AWS Organizations>Services>Single Sign On and make sure "trusted access" is enabled, if that is enabled, then it may be a permissions issue, in this guide https://docs.aws.amazon.com/organizations/latest/userguide/services-that-can-integrate-sso.html you can check the role and it's permissions
In the AWS Fleet Manager documentation, it mentions -
Fleet Manager supports AWS SSO authenticated RDP connections in the same AWS Region where you enabled AWS SSO
I have instances in multiple regions and it wasn't until I re-read the docs that I noticed this colossal limitation and understood why I wasn't getting anywhere. I'm guessing you're in the same boat.
The regional limitation of SSO is also mentioned here.
I'm still finding it hard to believe such a fundamental feature isn't supported by AWS SSO 😢
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