Colibri imx6 audio output

We have 6 IMX6DL modules flashed with the same WEC image and we have the following issue trying to use two audio outputs on our board (speaker/buzzer and 3.5mm headphones):
One module works for both speaker/buzzer and headphones
One neither speaker/buzzer and headphone works
Three only headphones works

Please let us know what the issue is.

We have an issue with output volume being quite low,
there is a fix that allows you to increase it using a registry key: