Revit doesn’t like to deal with an array that has 1 instanced element or component (although there is one exception). The array will break. So, the way to handle it is to have a separate single instance of a component for that scenario, and then the actual Array for whenever you need two or more instances.
To accomplish this, you need
some formulas to hide or show the required elements, and
another formula to maintain the array at 2 or more.
It looks something like this:
That particular example also caters for some other ‘switches’ that may turn off the array (notice the if-or formula.)
