I dread to say I am having the same problem again, and this is three years in a row.
Starting late again, no choice really as spring was so cold, and then high temperatures during fruit set in the greenhouse. I am not seeing it at all on the outdoor fruit - although not that many of them have ripened yet either, so it may still show up I guess.. They're mostly small fruit or cherries though which I believe are less susceptible...
Some varieties are affected more than others, some not at all, others a little...You can see the damage always on the same side of the fruit in one corner so it has something to do with heat or shade or both afaict. And I have two plants in one container which are the worst of all, maybe beyond salvage.. not sure why they were so much worse affected because they are very similar to their eight siblings in every way except they had a bigger container and more resources.
And a bigger crop of much more useless fruit.
Ho hum.
As for salvage, you can cut away the unripening parts and make sauce of the rest, if you dare or care to do it.