If you set up a pin with a transparent (blank) png file as it's image under "Pin Type", then the pin can no longer be clicked on to select it or view it. If the pin was hidden before it was made blank and bugged, the "hidden outline" can still be seen where the pin was made. If you double click a pin bugged like this, it will still open up a
linked handout. (or give the "Handout not found" error message if none
is linked)