In my experience with Stardust it will loose it's leaves if kept dry and cool... but then it does really badly the next year and struggles to grow again, so it has less leaves on smaller canes by the end of the next growing season. It losses those again and the year after grows less on even smaller canes.
For my parent plant by September last year it had no growths that year from the base of the plant, and only tiny patches of green (each no more than 1cm high) which were keikis trying their best to grow. Yes it had mites as well by then, but when I've looked back at my records I realise it was in very poor condition already before those appeared (probably why they could take hold).
I've had some keikis of it which accidentally got very different treatment. I had been advised to not give a winter rest the first year while they were tiny. So I kept them warm and watered as usual (when they dried out). I then sort of forgot about them, and they stayed in the house for the next couple of winters as well getting watered with all the plants that don't get a winter rest.
So this winter when I decided to stop fertiliser in August I still kept them in the house and still watered every couple of days with rain water, so the lack of fertiliser was the only change they got... and I got flowers on several of the keikis... in fact I've just spotted some more buds forming on one that hadn't flowered. Then in early Feb they started putting in strong growth and I started fertilising again and they have now probably put on more growth than the parent did in a whole growing season following a dry cool rest.
So why... all I can think is that one of the other parents is having a strong influence