Having created and defined a Title Block in a Drawing Template, some of the text fields of the Title Block cannot be double-clicked for editing.
Solution
Open the template and select "Menu > Format > Layer Settings" to make the layer containing the Title Block selectable. Right click the Title Block and select Edit Definition. Check to see if the Labels that could not be edited in the Title Block have a padlock symbol for their Lock Status.
If they are locked, select the Label and then uncheck the "Lock" checkbox (above the list of labels). Choose OK and try editing the text field. You should now be able to populate the fields.
Notes and References
Hardware/Software Configuration
Platform: INTL64
OS: window
OS Version: 764SP1
Product: NX
Application: DRAFTING
Version: V1847
Function: AUTOMATION
Ref: 002-7008389