Going back and forth into Calculation widget breaks it: displayed values are weird

I've been trying to set up a calculation widget but have repeated problems. Yes, I've cleared by browser cache repeatedly.

If I go in and type commas between values for an average calculation, it doesn't work because the calculation widget sees those commas as text. You have to click twice on commas to turn them into separators. This is not explained anywhere and is confusing.

Further, if I go back into the calculation a few times, for example to change the # of decimal places to display, eventually the widget breaks and displays the "copyright" © symbol around the calculation and the raw data separated by text commas. I then have to re-do the calculation all over from scratch, which is  big time waster.

See screen shot https://www.dropbox.com/s/r44incghn6yq0xc/Screenshot%202016-11-23%2015.50.34.png?dl=0

I am continuing to work on this form and cannot have it broken like this. I've cloned the broken version of the form here - please examine.

https://form.jotform.com/63277614055962

I checked it using a cloned version of your form https://www.jotformpro.com/form/22818026430952 and it seems to be working now as it should.

The calculation formula is good.

Please let us know if still not resolve.

Thanks.