Dev Mode activation: Individual developer account has no access to "Manage Xbox devices" (xboxconfig/devices redirects to Partner Center home)

I registered as an Individual developer through the free onboarding. My profile is verified (Seller ID 37622070) and I have since enrolled in the Windows program in Partner Center, which now works.

I want to activate Developer Mode on my retail Xbox Series X using the green Xbox Dev Mode app. The problem:

• partner.microsoft.com/xboxconfig/devices (and /xboxconfig/devices/index) redirects me to the Partner Center home page.
• aka.ms/activatexbox also lands on the Partner Center home page.
• My home page only shows the "My access" workspace.
• I don't see "Dev devices" or "Manage Xbox devices" under Account settings > My access.
• Retrying enrollment at developer.microsoft.com/microsoft-store/register fails with BDK_E_ACCOUNT_ALREADY_EXIST (ErrorCode 65115, "A billable account already exists for this identity", Retryable: false), tracking GUID 44d5b7ee-4b1f-480d-8680-c9999ccf4522.

What I already tried: signing out/in, private window, Edge and Brave, the Windows program registration.

I could not open a support ticket: the Partner Center AI assistant does not support Microsoft personal accounts, and Engage Center never finishes loading for my account.

Question: how can my Individual account get access to the Xbox devices page so I can enter the activation code? Is there a step or permission I'm missing, or does Microsoft need to link my account to a workspace?