AWS Transform web application works correctly, but the AWS Transform dashboard in Visual Studio does not load any profiles in the profile dropdown.

As to my understanding, the fact that aws sts get-caller-identity works confirms your core SSO authentication is perfectly valid. An empty profile/region dropdown in the AWS Transform Dashboard is typically caused by service-specific IAM restrictions, regional availability, or network routing issues.

I would try the following troubleshooting steps:

1. Verify Regional Availability and IAM Permissions AWS Transform is a specialized service currently available only in select AWS regions (such as us-east-1). The dropdown populates based on the regions your SSO role is allowed to access for this specific service.

• Action: Verify with your AWS administrator that your IAM Identity Center permission set includes explicit permissions for AWS Transform actions. Additionally, ensure there are no Service Control Policies (SCPs) restricting your access to the specific regions where AWS Transform is hosted.

2. Check Corporate Firewall and Proxy Rules While your standard AWS Explorer endpoints (STS, EC2, S3, etc.) are successfully passing through your network, AWS Transform utilizes distinct, newer API endpoints.

• Action: If you are on a corporate network or VPN, ensure your firewall or proxy is not blocking or performing SSL inspection (deep packet inspection) on traffic destined for the AWS Transform API domains.

3. Inspect the AWS Toolkit Logs To find the exact API error preventing the dropdown from loading, you should check the local Toolkit logs rather than relying on the UI.

• Action: Navigate to %LOCALAPPDATA%\AWSToolkit\Logs on your machine. Open the most recent log file and look for errors (such as AccessDeniedException, Timeout, or proxy failures) that occur at the exact moment you open the AWS Transform Dashboard. This will tell you exactly which API call is failing.

Since the web app works and standard AWS Explorer connects without issues, we can rule out IAM, networking, and regional availability. Your underlying infrastructure and access rights are perfectly fine. The fact that the logs show no Transform-specific errors and the dropdown remains completely empty points strongly to a client-side bug in the AWS Toolkit for Visual Studio version itself. Specifically, the Transform Dashboard UI seems to be failing to read or render your locally cached IAM Identity Center profiles. Similar issues (like existing profiles failing to populate in dropdowns despite valid STS tokens) have been reported in the AWS Toolkit GitHub repository before.

As a workaround, you could try removing the SSO profile completely from your %USERPROFILE%\.aws\config and credentials files, clearing the Toolkit cache again, and re-authenticating entirely from scratch using the dedicated AWS Transform Getting Started panel rather than the general AWS Explorer. If this doesn't force the UI to recognize the profile, I recommend opening a bug report directly on the aws/aws-toolkit-visual-studio GitHub repository -> https://github.com/aws/aws-toolkit-visual-studio/issues referencing this exact behavior, as this is an IDE extension rendering bug rather than an AWS configuration problem.

Based on the information available, there are a few troubleshooting steps you can try to resolve the profile dropdown issue in the AWS Transform Dashboard:

First, verify that your AWS Transform profile is correctly structured in your AWS config file. The profile should be located in ~/.aws/config and must start with [profile followed by the profile name. For example:

[profile example]
region=us-west-2

If the profile structure is correct but the issue persists, try rebuilding Visual Studio's internal cache files, as extension updates can sometimes cause cache files to go out-of-sync:

1. Close all running instances of Visual Studio
2. Open the Developer Command Prompt as an Administrator
3. Run the command: devenv /updateconfiguration /resetExtensions
4. Wait for the command to complete
5. Restart Visual Studio

Additionally, ensure you're using the dedicated AWS Transform authentication panel in the Getting Started page. Navigate to Extensions → AWS Toolkit → Getting Started, then select the AWS Transform authentication option. You may need to create a new profile specifically for AWS Transform by entering your AWS Transform start URL (which should have been emailed to you when you were added to IAM Identity Center).

If you're still experiencing issues after trying these steps, you may want to check your firewall and proxy settings, as these can interfere with AWS Toolkit functionality. You can also collect AWS Toolkit logs to help diagnose the specific issue with the profile dropdown not populating.
Sources
Modernizing .NET using AWS Transform in Visual Studio - AWS Transform
Troubleshooting the AWS Toolkit for Visual Studio Code - AWS Toolkit for VS Code
Troubleshooting the AWS Toolkit for Visual Studio - AWS Toolkit with Amazon Q