that's probably my benchmark. i installed that on a full-fat ubuntu 18.04.3 desktop image, and left all the amdgpu-pro installation stuff as the defaults, so maybe there is something going on with the flags you set (or Navi doesn't like running headless.)
If you want to stay on amd/radeon long term, it's probably better to sell your Navi card for a Radeon VII or wait for the CDNA (Arcturus) cards, as they are the ones ROCm will be supporting as they are made for compute vs. gaming. I bought the RX 5700 XT as an experiment, and ended up with Radeon VIIs instead.
If you want to stay on amd/radeon long term, it's probably better to sell your Navi card for a Radeon VII or wait for the CDNA (Arcturus) cards, as they are the ones ROCm will be supporting as they are made for compute vs. gaming. I bought the RX 5700 XT as an experiment, and ended up with Radeon VIIs instead.