Replied 21 March 2019, 3:07 pm EST
Our developers have confirmed that this bug happens because logic get editor and check editor.Isvalid of sheetview when set value. When get Editor, spread should recalculate for Conditional formatting (CF) to compose style. With the large CF range ($B$8:$Q$3000), spread should re-calculate for multi cell from ($B$8:$Q$3000) so this issue happens. Hence, you should use logic set value from cell like below.
Hence, please change the code in the button3_click with this code to resolve the issue:-
private void button3_Click(object sender, EventArgs e)
//sheet.SetValue(i, column, 10.0);
sheet.Cells[i, column].Value= 10.0;
Hope it helps.