[FFmpeg-user] Trouble converting from DNxHD36 to h.264

[Media Mouth]

Having trouble converting from DNxHD36 to h.264/mp4 and h.264/mov

Code used
> ffmpeg input.mov -strict -2 -b:v 8000K -vf format=yuv420p -c:a aac output.mp4

Picture comes out green or purple with horizontal lines

I'm on an older version MacOS (no choice.  Specs below).
I'm running same version MacOS on a different machine across town, where FFmpeg works just fine, so I'm curious what might be the cause of the problem.  Perhaps not installed correctly?

Including a screen grab here, but not sure if it will post...



System specs:

MacOS Mojave 10.14.6 (18G103)

ffmpeg version 4.4.git Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple LLVM version 10.0.1 (clang-1001.0.46.4)
  configuration: --disable-x86asm
  libavutil      57. 27.100 / 57. 27.100
  libavcodec     59. 33.100 / 59. 33.100
  libavformat    59. 25.100 / 59. 25.100
  libavdevice    59.  6.100 / 59.  6.100
  libavfilter     8. 41.100 /  8. 41.100
  libswscale      6.  6.100 /  6.  6.100
  libswresample   4.  6.100 /  4.  6.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...