Same issue for me, I was only able to upgrade a single repo - I have quite a number of them and I'd like to switch them all from webhooks to actions 😄
I believe I'm seeing the same thing as well. New repos appear to have new workflows, but all of my old ones do not. An organization I'm in also just got access to the beta, and even its older repos are using the new style, so perhaps I'm in a weird limbo too! 😬
If this happens to anyone else, you can get around it by creating an HCL syntax workflow. Then you'll see the option to upgrade. You need an old-style one and then it will just offer it and you can move forward without waiting for staff to upgrade you manually.