I have tested your issue. But in my side i can able to upload more than one image without any error. How many filed you are using in your form?. You can test with only one post body filed in one form. If the problem remains then please let me know.
And the other point is the row and column number of the filed. I tested and failed to reproduce. I will notify to our developer team about this matter. Hope they will fix it in our next update.