AME rendering 4k to H265

We are attempting to render a 4k file to HVEC (H265) on a macbook pro:

2.7 GHz Intel Core i7,16 GB 2133 MHz LPDDR3,

Radeon Pro 455 2048 MB

Intel HD Graphics 530 1536 MB

CC 2017

Render preset:

We have been experimenting with the bitrate but all seem to do the same thing. The results are very poor, green flashes, pixelated and will not play smoothly.

Any help would be appreciated.