[HELP] after encoding ass into mp4, but there is no subtitle at all

[Selur]

If you do not want the black bars in the file: crop them before the subtitles get applied
If you want black bars and the subtitles higher, you got multiple options:
a. adjust the positions in your subtitles
b. crop, add subtitles, add borders back (to archive this you need to also make sure to change the filter order, so that 'Letterboxing' is below 'Adding Subtitle')

Cu Selur