@PUNKEY,
It is incredibly difficult to keep slugs and snails away from small plants once they are planted in the soil of my garden, so I keep them in pots which I protect from slugs and snails by various methods. In fact it is only the 'climber' which is still in the pot, the rest are in makeshift tubs.
All of the other ones grew normally and produced their mini-tubers as I was told they would, it was only this one which went strange.
It attached itself to all of the weeds growing in the pot and also some of the larger plants growing in nearby pots.