How to upgrade to Game Pass Ultimate?

Hi,

I recently redeemed 2 Years + 14 days of Xbox Live Gold from codes I had plus 30 Days of regular Game Pass.

I was under the impression that I would be able to upgrade this to Game Pass Ultimate for $1 since my Xbox displays $1 as the price to upgrade it.

However, I'm getting an error that just says

"It looks like something went wrong, but we can help".

I've used the $1 promotion before, but since it says $1 again, I was under the impression that I could use it again. How do I upgrade to Ultimate?

Note: Even if I can't use the $1 upgrade deal anymore, can I still upgrade to Ultimate for the regular price at $15?

:)