Aronia Berries no good

I'm afraid I don't have a picture but I have a black/purple Aronia which I think might be the Viking variety which I inherited. There are 2 problems which I assume are related. The first problem is that the flowers don't properly bloom. They are very numerous and the bees love them, but the petals never really come out. As the berries grow they appear absolutely fine but when you break them open they have very little flavour and have a pale pinkish brown, cotton wool like texture which I assume is not right. The soil is clay based but I have done quite a bit to improve it over the last 3 years that I have lived there. The plant is in full son and when dry I water as regularly as I can (during hot periods this is usually daily). The plant is mature and must have been there a number of years before I moved in, I suspect. It is about 3-4ft from a relatively mature elderberry tree and I have wondered if perhaps that is sapping neutrients from it? On the other side, roughly the same distance is a mature rose bush. The plant is growing well and I don't see any signs of distress or disease on the leaves. If anyone has any ideas on what I wrong or how I sort it out that would be great. I know Aronia isn't that commonly grown so this might be a bit of a long shot! Many thanks in advance to anyone who can help me. I'm desperate to make Aronia gin!