When you say it doesnt empty is it leaving it full of water or full of softner still?
Ok if its leaving the softner in there then the dispenser roof will be blocked up.
What you need to do is remove the dispenser drawer.
From there look inside the dispenser box at the roof just above the softner section.
There you will see some holes. You need to get something long and thin and flexible like a cable tie or strimmer wire and push it into the hole in the dispenser roof.
Push it as far down the roof of the dispenser as you can and this will clear the water channels in there.
Once clear retry the washer and im sure that will sort the problem out. As what happens is you can get a blockage in the water channels in the dispenser roof so when it should take the softner the water goes through a different channel instead and thats why it doesnt take it.
So doing the above will clear the dispenser roof and sort the fault out from there for you.