"Error On Missing Links" not working in PDF task

1600 sheet project, at last minute we noticed link missing on prints.  This resulted in panic and having to print manually and issue late to the client.  Management is not happy with Clarity now.

When I open one of the Revit files on task server I get the missing link error but the tasks still ran even though the "Error On Missing Links" is on.

At some time the missing link must have become corrupt on some, or all, of the task servers although we did not notice on production computers.