When you add a VI to a polymorphic VI, the highlighted VI in the "Instance VIs" is not the one you just added (unless the polymorphic VI has only one instance VI). To recreate issue: create a polymorphic VI, add two instance VIs to it, now add a third - when you add it and return to the plymorphic VI editor the 0th VI is selected (expected behaviour: the newly added VI is selected). This adds an unessisary step when editing the name of the instance VIs (especially when you have a polymorphic VI with over 20 instance members).