Your comment regarding protection is NOT irrelevant as the type of Protection that you mention is ONLY designed to be used with Legacy FormFields.
Further "Developer>Controls" does not identify the type of controls that you are using as Content Controls, Legacy FormField or ActiveX?

are all inserted from the developer tab of the ribbon.
However, I believe, from the screen shot included in one of your responses, you are using Content Controls.
If you send me a copy of the document, referencing this thread in the covering email message, I will investigate the issues that you are having.