ffmpeg and blocky corrupted video clip after concatenation

Question

I am attempting to concatenate a bunch of video clips using ffmpeg. The command line I am using is:

ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4

One of the video clips in particular appears corrupted and blocky in the output file, or sometimes doesn't even display (VLC). The video clip plays fine (VLC) on its own. The details are below. Note, it is 2.02s in length; that is expected.

Any advice? Do I need to re-encode this video somehow and to what?

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'master3-1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.18.104
  Duration: 00:00:02.02, start: 0.000000, bitrate: 1789 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 1670 kb/s, 15 fps, 15 tbr, 15360 tbn, 30 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 129 kb/s (default)
    Metadata:
      handler_name    : SoundHandler