I tried to upload 3 pics could not so here is the 2nd and one more coming.

Last one

I too have lost 1/4 to 1/3rd of my pumpkins. I don't know how things are in your area but here in WI it has been so hot and dry. Much more than normal. I water deep 2-3x a week but the soil is still dry. I believe the plants are stressed and aborting fruit to save themselves and what fruit it can. If it can't sustain the fruit it will abort it. So something, weather, bugs, lack of nutrients is causing your problem. How does the foliage look?

The rinds don't look damaged. I bet it was some kind of disease .

The leaves are all green and hardy, healthy. I water only about 1 time per week.