4K file export goes wrong

[flbs@mail.dk]

Hi,

I have a short Mavic 3 video clip in 5.1 K, that I want to export including a sound track as H265 4K.
The resulting MP4 file only shows the first framew frozen, but sound is playing fine. I can't find a solution.
My system:

Nvidia GeForce RTX 2060 driver 536.40
AMD Ryzen 9 7950X 16 core 4,5 Ghz. 32 Gb RAM

Premier pro version 23.4.0 Build 56

Any help is appreciated.
I tried for fun to download Davinci Resolve free and the MP4 file was fine.

[flbs@mail.dk]

No suggestion at all??? 
When I play the timeline in edit it runs OK, but running the timeline in export the video is stuck.
Where else can I get help. I pay quaite a bit every month for these programs, and Premier does not work. Frustrating.