SOLVED: Direct Play 4K HDR Issues

[theguymadmax]

It likely does support it; it's just that the Shield doesn't report it.

Code:

 Decoder "OMX.Nvidia.h265.decode" supports
    profile/levels: [
          1/131072 (Main/High 5.1),
          2/131072 (Main10/High 5.1),
      4096/131072 (Main10HDR10/High 5.1)}

The Shield reports a maximum level of 5.1. The ATV client relies on these HEVC level checks and will transcode accordingly. As mentioned in that thread, there is no current workaround. There are several proposals, but none have been implemented.