Hi There i am suffering from a problem of Limit of 5 columns in Child table or grid of FRAPPE/ERPNEXT

Please someone help me on this problem that how can i increase the number of columns in Grid.
1: This problem occurs in existing child table that does not allow me to add more than 5 columns in Grid.
2: if i create a new child table then it let me allow to add to grid more than 5 columns.
3: The ‘Add to Grid check box’ is not appearing in existing child table.
4: while The ‘Add to Grid check box’ appearing in new child table.