I have been making some truck shaped cookies all year for somebody and for some reason when I put my RI on around the top of the door of my truck (I leave a square to fill in later with white RI for the window) the icing seems to be collapsing and leaving a caved in hole around the top of the door of the truck cookie. It has never done this before and now it seems to be doing it in the same place on every cookie. Any ideas? (I am making my RI slowly with a beater for 10 minutes)
Could you snap a picture and post it? It would be much better for a definitive answer.
If this is a case of too much air in your RI - it had now enough time to get the air out. Half to one hour is enough. Don't re-beat it, mix it only (either with wooden spoon or with dough hook(s) on your mixer.
I have had that before when I have put too much water in my RI. It 'sinks' in small areas when it dries. My suggestion would be to use less water.