I don't understand. In an earlier post, you said:
I understood that if a check box is available and checked in C20, inserting a row below or above row 20 creates, in the new row, a
checked checkbox.
Your current comment seems to contradict that.
What I get is as I described: the checked/unchecked value is inherited if & only if the entire column is formatted as checkboxes. If not, only the checkbox format is inherited & the new value is always unchecked, regardless of the value of the "parent" cell's checkbox.
This occurs whether or not I use the 'insert a row above/below' popup menu items from the arrow that appears when the cursor is hovered over a row label, drag the tab at the bottom right of the table downward to create one or multiple new rows, or with any other method I know of to create new row(s).