hi there - do you hear the pump pumping and glugging when it is supposed to on the last rinse of the wash cycle - is the softener you are using very thick in viscosity or is it runny like as in water? - if it is thick or it says on front of bottle 'concentrated' then try watering it down to make it runny.
is it doing the problem on all washes ? , some wash cycles do not take in the softener by design . try some other washes like normal cotton cycle.
Good luck
