**Ad 1:**

Try adding the `-pix_fmt yuv420p10le` option (e.g. before `-vf)`. Or only `-pix_fmt +` for using the same pixel format as the input video has..

If it doesn't help, *you obviously have an inappropriate, albeit more common FFmpeg version — only for 8-bit colors.* (Your original video uses 10-bit colors, and FFmpeg will try use the best 8-bit pixel format in this case - with the colors' degradation, of course.)

FFmpeg may be built for 8-bit colors or for 10-bit colors, or — in recent time —  for both of them (for your HEVC encoded video). 

So you need to build (or obtain by other way) version for 8-/10- or 10-bit color depth. 

**Ad 2:**

Bitrate of `1700` is *very* low - only 1700 bits per second, i. e. about 212 bytes per second. 

To reach such a low bitrate and at the same time reach your `23.98` frames per second, the encoder is limited with  average size for 1 frame about 212 / 24 = 9 bytes only! 

Did you see a picture of such small memory? It has almost no information, so the gray image.

You probably wanted 1700k (Kilobits per second) — or, more probably — 170k:

    -b:v 170k

so correct your command in this way.

**Addendum to Ad 1:**

You use 4:2:0 chroma subsampling. Try the maximum quality, i.e. 4:4:4 (no subsampling), or - maybe it will be sufficient for you - 4:2:2.

To reach this, use `-pix_fmt yuv444p10le` and change the video profile to main444-10 (with option `-profile:v main444-10`).