There's a bug where you can't delete changelog entries. It's trying to post /p//deleteupdateajax instead of /p/1160672/deleteupdateajax.
https://i.imgur.com/eGSfE8Q.png
Saving an edit works because the productId is hardcoded into the function (when the page is rendered I guess).
http://i.imgur.com/hKYqN24.png
Where as delete calls var productId = $modalPpload.attr('data-product-id'); which isn't set for either button.