All audio tracks in a sequence use positional audio played from an emitter. However, if your sequence is not perfectly aligned with the room and the default emitter position, then you might hear your audio as only playing out of one speaker, the wrong speakers, or is at least offset in some way from where you were expecting it.
This is not a bug, but it is something you will need to account for/control, so here we show how to do this properly by setting the listener's position and orientation.
First we will position our listener in the centre of the game window, so that we hear positional audio play across both speakers as the sound source moves:
audio_listener_position(window_get_width()/2, window_get_height()/2, 0);
Then we will flip the "up Y" orientation from the default 1 to be -1, so that we're now "looking into the screen" and sounds will play out of the left/right speakers as players will expect:
audio_listener_orientation(0, 0, 1000, 0, -1 ,0);
(You could also use this line in combination with your game's Options screen as a way of allowing your players to align sounds to their individual speaker/headphones setup, in case they have them plugged in the wrong way around, etc.)
Be aware also you can create other fancy effects by playing with the argument values you supply to the two above, and you can also apply different audio falloff models which will further shape how your audio sounds.
Remember that you may need to reset the position/orientation values when the sequence has finished playing!
We have attached a very simple sample below which just shows the above two functions being used (it does this within the Sequence's Create event function), so you can try that on your system and then use the information here to refactor your own code.
For the fancy stuff you can do later on, start by checking out the manual page for Listeners.