Mine did the same thing last year though it's newer than yours. I'm blaming the mild winters and the wet. Can't think of another reason but someone else on here will come up with other ideas.

Hi, welcome to GoY, reasons for not flowering are varied, but can include the soil being too dry when the buds are forming in late summer, which can cause them to abort, sharp frost in spring can cause any buds you have o drop before opening, other possible causes are; too much shade, not enough potassium in the soil, try treating the soil with sulphate of potash in spring at 20 grams per square yard, as you say th new shoots are coming from the base, it could be that the graft has failed, {if you have a grafted plant, not all are,} if this is the case, then you will need to get a new plant, have a look at W amethyst falls, and buy any new plant whilst it's in flower, it may not flower for a year or two, but this is quite normal, it will flower, Derek.