Yikes, that is weird! But other fruit on the same plant is developing normally?
Two thoughts come to mind, *total conjecture*
1. They have "cooked" on the vine in excessively hot weather (yes, that can really happen), possibly during a window when they got slightly less water,
2. They are way over ripe. Should already have been harvested.
3. Both 1 and 2. That happened to me a couple of years ago. They didn't look quite like that, but they stayed yellow from sun scald so I thought they hadn't ripened, but actually were over ripe and turned to mush when I touched them.
Looking forward to seeing if you find the answer!
