ProSteel Drill - Diameter cannot be overwritten. Only the diameters in the list are possible to choose.
ProSteel options - Hole diameter restricted to the available list.
1. Open the Global Settings or Options by holding the right mouse button in the View window and then click on the Options.
2. Under the Dialog Settings page, enable for "Allow override of values in Hole Diameter list". This will allows setting any hole diameter. If this field is not checked, you can only specify hole diameters from a given list.