Cannot create a Microsoft Store app: Entra permission error and inaccessible support portal

I use a personal Microsoft account with an existing Microsoft Store developer account. When I select “MSIX or PWA app” and try to reserve an app name, I receive an error stating that I do not have the required Microsoft Entra Identity permissions to register an application.

I also cannot contact developer support. Engage Center stays on a loading screen, and its service menu is blank. The same issue occurs in Edge InPrivate. The Help panel shows documentation but no contact option.

What is the correct way to resolve this for a personal developer account, or contact the support team? I want to register a non-game app.