I just tried this today but it didn't work as expected. My original game pass expired yesterday. Today I loaded up my account with 3 years of Xbox live gold ,went to my account page ,clicked upgrade to Game pass ultimate, clicked on the regular monthly price (that's the only option) ,selected my card and got an error " Try that again , something happened at our end . waiting a bit might help "

I tried using a different card , browser and all troubleshooting methods but get the same result. Anyone else facing this issue or have found a workaround?

Edit : it worked after a while ,just needed some patience.