Cannot download 4k on Amazon prime video even if my internet speed is past 30Mbps

[Svenskaz01]

Hello, I downloaded a copy of grand tour which supoosed to be 4k, but adter downloading, it says 1080p hd only, any solution on this? 

[nessie2]

I just got my XZP today and same with me, if i start a stream it says UHD for a second then changes to HD.  I have a 40mbps connection so not a bandwidth issue.  Have you had any luck with a fix?