Why does audio fall off when rewinding a video compiled with ffmpeg?

Question

fmpeg

I collect video from two containers. From one I take a video sequence, from the second audio and subtitles. The resulting video plays correctly only sequentially. If you jump to an arbitrary point, audio and subtitles fall off.

The video files are identical in timing.

ffmpeg.exe -y -i as.mkv -i hd.mkv -codec copy -map 1:v -map 0:a -map 0:s final.mkv