Lightroom :: 4 / 5 - How To Lock Altitude When Moving GPS Coordinates On Map

I have recently imported pictures *.CR2 with *.XMP containing GPS coordinates and altitude information.
 
From my last import (LR4.1 or 4.2) I remember that I was able to drag pictures in the Map view adjusting GPS coordinates, without touching altitude information which was what I needed.
 
Today I discovered that as soon as I move an image on the map, the altitude value is automatically deleted. And this happens in LR4.3 and also in LR5.0. I understand that if you change the GPS position, the altitude changes also, but for adjustment I have to make, there are no big altitude changes therefore keeping the original value for me is good.
 
Is there a way to "lock" altitude number, in order to keep the original value, when moving photos on the map?