I didn't get all of the conversion from mkv to mp3

[vlc man]

I have 1hr 1 minute mp3, but the original source file (mkv) is 1hr 33 minutes. Why did this happen?
I used option Audio - mp3 and prefer it.

But I tried different format like:
Video-H.264 + MP3 (MP4) option but only got 14 minutes using convert for this option for same mkv original source which is 1hr 33 min long.
Time limits in preferences is set to zero values.

It keeps asking me to pick between Over Write and Existing file already there (something like that) over-and-over
I am not sure if I have the latest version VLC 3.0.21 Ventinari

Distributor ID: Debian
Description: Parrot Security 6.2 (lorikeet)
Release: 6.2
Codename: lory

Thanks in advance.