@schmucke @chris
hi,
normally this can be caused by a problem with the data the app receives from a device. you can go to your iphone - settings and at the bottom in the app list there should be pimate and you can switch on the recovery switch to completely reset the app or the clear favourites switch to remove all the devices from the start screen.
if you have enabled to share log data with developers on your iPhone i should be able to see where the error occours, if not I would try to add the devices one by one and tell my at which device it fails so i can narrow down the problem