When one of our employees is out of office, our name in SFDC changes so people can easily see that we're not around.
Unfortunately, this is breaking our "Create Task" flows and assigning leads to our Default Lead Queue instead. The chance of someone missing this is pretty high depending on the campaign's goal.
Does this work only with names, or can it be their user ID?
I would bet that this is not linked to the fact that the name of the user changes (AFAIK, they are referenced by ID). It is linked to the fact that the user is likely temporarily disabled in SFDC, and therefore Marketo cannot assign a task to that person any more. This is reflected by the fact that the assignment no longer works either and the lead is assigned to the queue.