How do I control NumColumns.?

Hi again,
In my feed settings, I am using “3 posts” and “3 columns” but in the output data-json attribute in the first <input type = hidden />, I see this:
“numColumns”:{“desktop”:3,”phone”:3,”tablet”:5}

…which means at viewport width of 769px up to 935px, the plugin displays 5 posts instead of the 3 I set.

Any idea why this happens and how to fix it?

Thanks