A very interesting experiment.
Have v5.40 (2d or 3d) on nuvi 710 with or without additional cards is the same (may be it is necessary to disconnect a map of Russia, I don't had it).
Tap "Tools - Settings - Restore".
Tap "Where to? - Adress" and get the screen "Select City in: - empty string - Spell City" and so on.
Tap "Spell City" and see what address search is working !!!
But if we tap "Change Country" and select Беларусь we get the screen "Select City in: - Беларусь - Spell City" and so on and address search became broken.
In oder to get a working address search we must to restore settings again.
This was not with maps v5.30.