mp4 (hevc codec) does not display thumbnails.

[dukekoks2]

mp4 (hevc codec) does not display thumbnails.
Can anyone tell me how to set it up?

[Marginal]

This app doesn't handle .mp4 files https://github.com/Marginal/QuickLookVideo/wiki/Troubleshooting#thumbnails-and-previews - they're handled by AVFoundation.

AVFoundation requires that HEVC parameter sets are stored in the file's "sample description" headers (see for example ¶1.10 here). But "HEVC (Parameter Sets in Bitstream)" indicates that the parameter sets are (or may be) stored in the video stream, so AVFoundation doesn't support this file.

If you're encoding or remuxing these files yourself using FFmpeg, try adding -tag:v hvc1 to the ffmpeg command-line.