sorry for the late reply, i was on holidays
i cannot reproduce the issue, neither on chrome nor safari
maybe it has to do with this: when you edit an element grid, you need to set the column gutter and row gutters for tablet and phone sizes also when clicking these buttons, otherwise they will have a default value of 1% i think:
0_1571057239993_Screenshot 2019-10-14 at 14.44.44.png
