Prime Video - Cannot see nor stream 4k/HDR content

[stoofa]

So the relevant components are:
55XE9305 TV. Yamaha RXV581 Receiver. PS4 Pro.

If I fire up Netflix, either on the PS4 Pro or native app on the TV all is well. I have a 4k category within Netflix and I can watch everything in it's full glory.
Netflix confirms 2160P and if I go into "Picture Settings" on my TV, I have the little HDR flag up to confirm that is also working (Brightness also automatically moves to Max).

If I fire up Prime Video, either on the PS4 Pro or native app things are very different. There is no "4k content" category to be found anywhere in Prime Video, all the searching I've done seems to indicate I should have that on the home page.
I've looked for known 4k/HDR content on Prime, so Grand Tour and Goliath. I cannot find a specific UHD stream and whilst streaming it only goes up to 1080P. On entering "Picture Settings" there is no HDR flag and the brightness has remained at 90.

It's almost as if Netflix is detecting the presence of 4k capable equipment, Prime video however is not. Is there anything that I can check? I cannot see any settings within the Prime Video app on either the PS4 Pro or the TV (someone on a different forum mentioned having to set "Best Quality" in the app, but I'm not seeing that).
HDCP 2.2 is fully enabled, not that I think that has any baring on things

Any thoughts?
Ta

 

[stoofa]

I'm at a total loss on this. The PS4 Pro I can almost understand, but the Native Prime Video app also having this problem is confusing.
I simply do not have a "Included with Prime 4k UHD HD TV" category to select. I've scrolled through every page of Prime Video and that category isn't there - which would indicate the app is not seeing a 4k capable setup. Something the Netflix apps on both the PS4 Pro and TV disagree with.
Green button doesn't do anything for me - I've got no filter options that I can find.

 

[stoofa]

I should have updated on this one.
So no matter what I did, there was no option for any 4k content within the App. I know Amazon aren't offering much, but it really was frustrating I couldn't find what little there was.
As it happened on Friday the latest firmware update for my TV went OTA (previously people were installing from USB). This update adds Dolby Vision, however some people have reported issues with built-in Netflix & Prime Video apps.
Anyway, did the update anyway, totally reset the TV and then inputting all my settings again.
Now the built-in Prime Video app (Version 4.4.0) is at last displaying the "4k UHD Content" option and I can watch this. I've not tried from the PS4 Pro again, however I'm reading mixed replies as to if the PS4 Pro Amazon App can actually output 4k anyway - so I'm happy enough with the app built into the TV.