The first two times I started the game, I didn't hear audio. For some reason, the third time and all times afterwards, I did and sound seems to be working normally.

When running in 8K resolution (which looks gorgeous by the way, especially the grass), the game frequently crashes (i.e., within minutes) with the following error:

d3d11.dll caused an Access Violation (0xc0000005)
  in module d3d11.dll at 0023:78f1aa00.

When I play in 4K or less, the game seems much more stable (tested for 30 minutes, no crashes - previous crashing happened within 2 or 3 minutes every time).