I'm still having the problem too. Anything saved in favourites is fine, but any new searches whether it be "locate caches nearby" or via GC code come back with a comms error!
Most annoying!
Within the desired cache choose "Navigate to Geocache>".
Then choose the little flag icon in the top right-hand side of the screen, this then allows you to add a way-point.
Dan.
I've noticed the exact same thing recently. It is a right pain, all of a sudden your position will just not update. I resort to going into the iPhone settings and turning off/on the location services for the Geocaching app.
grrrr!!!