6.0 Marshmallow – The phone automatically turns off in some places

Curiosity: at this location (False Creek, Vancouver, British Columbia)

Google Maps

my girlfriend's mobile phone (Android Moto X) turns off automatically. When manually restarting (reactivation), once powered on, it automatically turns off.

If we move for example ~ 75-100 feet away, does the phone work normally?

This happened twice, when we tried to photograph foliage.

What would cause that?