I agree, this part of the application is not the best one… But it works for me as long as each value you entered matches the type verification. Did you use data types like date or number? If there is any format exception the value should be colored red instead of black indicating a parse exception.
Does the issue remain if you use String typed columns, only?
I just added a few rows on your table of Aggregate MashApp, complying with the format. So it was another name with different days for three months. So as I filled in string, date and integer, I don't really know if in some cases, the table could have different behaviour.