for mobile phone use, I prefer to convert whole albums
to a single file using the Opus codec. So I have one
.opus file (which consists of concatenated ogg files)
per album.

I use the newest foobar2000 (1.5.1) on Windows as
frontend to do the conversion.

In the beginning, everthing seemed to be fine.

However, if I want to go back to the beginning
of the currently playing song (e.g. song 5 of the album)
by sliding the navigation slider of that song to the
far left, the music begins to play from the beginning
of the album (the beginning of the first track)
while all information visible on the screen
makes it look like song 5 were played.

So "what you hear is not what you see" ;-)

This unexpected behaviour is the same in
"foobar2000 Mobile 1.1.55 on Android 9"
and in "foobar2000 (1.5.1) Windows".

Moreover, trying to navigate back one song using
the "one track back" button, the music also
starts playing from the beginning of the album
in "foobar2000 Mobile" whereas it starts correctly
from the beginning of the previous song in "foobar2000