Variable Inheritance Failure: 3Box Template failing to resolve {placeholder} from 2Box (TriCaster ME workflow)

[leo.yon]

1. Objective My goal is to implement dynamic variable inheritance between Viz Mosart templates within the scope of a single story (slug).

• The "Sender" (2Box Template): This template is assigned to TriCaster ME2. It consists of two layers: one for a guest source and one for a dynamically assigned clip source (e.g., Clip A or Clip B selected by the journalist in the NCS plug-in).
• The "Receiver" (3Box Template): We want the subsequent 3box template to automatically inherit whichever clip source was used in the previous 2box for one of its layers, eliminating the need for the journalist to select the same source twice.

2. Setup and Initial Success Following the official documentation for variable inheritance, we configured the following:

• Sender Configuration: In the Template Editor, we added a Newsroom Tag named broll to the Switcher XPoint of the clip layer in the 2box template.
• Receiver Configuration: In the 3box template, we used the reference syntax {broll} in the XPOINT field of the "Key/Layer" device (configured for TriCaster 4-layer ME).
• Verification of Broadcast: We have confirmed that the "Sender" is working correctly. By using the shortcut Ctrl + Shift + Alt + Double-click on the 2box element in the Mosart UI, the execution XML clearly shows: <field name="broll" value="S_RIP" /> (or the specific Clip name). This proves the variable is successfully being broadcasted to the story scope.

3. The Problem and Attempted Solutions Despite the variable being available in the story, the 3box template fails to resolve it. The broll field is entirely missing from the 3box execution XML, even though the other three layers (using fixed sources) are generated and execute correctly on the TriCaster.
We have already attempted the following troubleshooting steps:

• Synchronization: Performed the RT (Reload Templates) command in the Manus Administrator console, restarted all backend services (Manus Admin, AV Automation), and reloaded the rundown in the UI using Shift + F12.
• Syntax Degradation Test: We tried the {broll}#S_RIP syntax in the 3box template. Even with a hard-coded default value, the logic engine continues to "silently filter" this field out of the generated XML.
• Template Integrity: Confirmed that the 3box is NOT an "Empty Template." It correctly recalls the ME and switches the other three fixed sources.
• A/V Setup Whitelisting: We suspect the logic engine blocks {broll} because it is not recognized as a "legal" source. We attempted to manually add an entry in AV Automation > A/V Setup > Video Config with X-point name: {broll} and a dummy physical input.

4. Questions for Technical Support

1. What is the correct procedure to register a {placeholder} string in the "A/V Setup" whitelist to prevent it from being filtered during XML generation?
2. Why does the 3box XML fail to produce a field node for {broll}#S_RIP even when the 2box has explicitly broadcasted a valid value for broll?
3. Are there specific limitations within the TriCaster driver (Key/Layer device) that prevent it from accepting dynamic placeholders for variable inheritance?