I try to make this question as simple from start then add info if necessary

Im playing through the campaigns in both original and the two expansions
and im wery disturbed that if i save, then load that save...the music that played
before (and was there only in the same session as i started the entire mission in)
is gone, and im playing in totally silence excluded sound effects.

Is it the same for you also? I have personally never seen any other game
in my career behaving similar actually.

Maybe this was the case from the beginning when i purchased this game...i don't remember
my first playtrough.
Maybe the music are supposed to only be regenerated to scripted events
with this small order interruptions... throughout the mission, cause something suggest to
me that i have heard music restart after this advance moments...

What is absolutely clear is that the music would never stop if i complete a mission
from the start gamesession without reload.