I have exactly the same issue.

Thanks very much.

Thank you Steve. So if Editable? is not selected, the column is read-only?

Thank you all. @LeventK Yes I have a formula. I guess it turns into read-only automatically. @Eloy_Paredes_Henriqu - I thought I have to select a box to make the column read-only but it seems because of the existing formula it turns into a read-only ...