Doesn't empty Fabric Softener from drawer - any ideas why not? When you finish wash and check drawer - it is still in it, and towels are by no means soft!!
I presume it has worked OK previously. Check that the holes where the water comes in to wash out the tray are not blocked. If not that then I am stumped.
The syphon tube that dispenses the stuff may be blocked or there is no water going into the dispenser on the final rinse - this starts the syphon off. (Shouldn't use conditioner on towels, btw.)
it is best not to use fabric conditioner on towels and microfibre cloths. The tufts are supposed to be well aerated to soak up the moisture so the best way to dry them is in the tumble dryer....towels are softer than air dried. If you use fabric conditioner then you are coating the tufts and so there is a barrier between the tufts and the moisture.....oh dear.....*goes off to look for a life*