SOLVED this problem having had it with two machines.
The conditioner is released by the water lifting the stopper. If the machine is not level the conditioner goes through but the remaining water doesn't as the stopper closes.
LEVEL THE MACHINE (using a leveller) front to back (most important) and also left to right by adjusting the feet by screwing them up or down.
Most people only adjust left to right so it 'looks' straight but if the machine is tipping backwards or forwards the stopper will not let all the water out.
I was amazed at how unbalanced mine was. By eye it looks fine but it was way out. If only I had known years ago!
It has worked perfectly now for weeks of continual use.