If it’s an actual dedicated server (not listen) then it does not do any rendering, graphics and sound wise. Since no player is actually sitting in front of the server and playing on that machine, it does not need to perform any sound/graphics operations. In other words sounds are not actually played on that server.
I guess you’ll have to use a timer instead.
Are you sure the second log is also from your server? Because it is no longer Role_Authority? Also it seems a bit weird that the time stamp (5.59) is the same for the three log statements (could make sense on the server since it basically finishes playing any sound immediately as they are never played anyways).