User Interaction Level resets during Data Merge
Using at the top of the InDesign tell block:
set user interaction level of script preferences to never interact
The way I understand user interaction levels, when set to 'never interact', it should suppress all dialog boxes from popping up.
When AppleScript performs 'merge records', and the merged record contains missing fonts, ONLY SOMETIMES a missing fonts dialog box pops up and breaks the script. One can close this dialog, run the script again, and the dialog doesn't appear. This unpredictability is why I'm logging it as a bug.
app.scriptPreferences.userInteractionLevel = UserInteractionLevels.NEVER_INTERACT;
I posted a more detailed explanation on the Adobe Forums here: