New form controls are disabled

Using Base, I’m trying to add a new control to an existing form that is tied to a database field. The control is inserted and I set the field source and other parameters as necessary. For example the Reference Value for a radio/option button. In Design Mode all seems ok but when turning Design Mode off, or opening the form, the control is disabled. I have double checked the Enabled parameter and it is Yes. This is happening with any new control (Text, radio, combo, etc.).

[Tutorial] Read-Only in Base

Integer_Option.odb (12.2 KB)

In the form the type is linked to a list box, a set of 3 radio buttons and a numeric field with spin button.