Photoshop CC Video Export

I have the same requirement of vertical 4K for which I found a solution. Since you never received an answer with a solution to circumvent the unwarranted limitation in Photoshop, I'm posting it here. I feel that answers should offer a solution, when there is one, rather than predicate a justification for the issue.
You can rotate the canvas, render the video horizontally, then re-render vertically the video with ffmpeg:

ffmpeg -i horizontal.mp4 -vf "transpose=1" vertical.mp4

Compressed formats like H.264 are "constrained" and use specific matrices and optimizations for different resolutions and framerates. You cannot always use any arbitrary setting and combination. You have to read up how this stuff works and adjust your work accordingly so it complies with these standards and can actualyl be exported and played back on standard devices. This has nothing to do with PS, it's a generic thing.

Mylenium