Die-back in Wichurana hybrids

I’ve been trying tot grow the Wichurana rambler Paul Noël for some years now (multiple plants). Each time it forms a reasonable branch that goes up to more than 4 feet it eventually dies back later in year.
Now I notice the same with an OP of Léontine Gervais (Barbier Wichurana rambler). It is 4 years old. It forms a lot of small branches from the roots. I have cut all branches but 4 strong ones this spring. They grew up to 5 feet and now they also die back. It is very frustrating. I just want to see it bloom once, so I can decide to cull it or not.

Maybe this die back is a trait of Wichurana species roses? It doesn’t seem to be related to any disease or pest. Maybe my sandy soil? We had enough rain, it wasn’t due to drought. Certainly not due to frost or cold.

Any ideas or experiences with Wichurana ramblers?

Sidenote: my Léontine Gervais does very well and hasn’t got this problem.

Die back of healthy, vigorous growth in Wichurana hybrids isn’t an issue I have ever encountered. Wichurana and multiflora are both extremely susceptible to crown gall infection and that has been a great issue for me but not the die back of canes above ground. I’d suspect a canker issue or perhaps weather associated issue. Could there be freeze damage showing up later in the season? Your profile doesn’t indicate where you are located, so I’m not sure if winter freezes may be issues there.

Belgium. I guess that 's zone 5B. Humid.
I don’t think its cancer. All are young plants.

Certainly no frost. We had one week in February last spring. All growth was new and formed this summer.

Maybe fluctuating drought and rainy periods?

Is die-back more common with wichuranas?

Not in my experience, as I previously wrote. Rainy periods could easily cause issues such as Downy Mildew and canker.