Only just found out that now its not possible to buy from Prime Video anywhere except the country where you’re account is based.
I’m in the UK but often buy content to create Blurays for things not available in HD outside the US . I delete all my debit cards, default to my US forwarding address and pay using gift card. Not anymore.
Now , if your account was setup on a non US Amazon site you cannot buy video from the US site at all. I’m guessing you can still watch US exclusive content thats free on Prime if you have a VPN
Edit : The C5 download finally worked but only at 480p , so a waste of time.
No idea what UTC is but last year when downloading a huge series from Netflix the daily limit renewed at midnight UK time