What I can tell from it: the map itself started (that pink is the blank map background with the kingdom tint on top), but none of the map tiles drew, and the Oil Wells show their health bars with no picture above them. I checked my end for that afternoon. The tile server answered every request, New York's included, and the game server logged no errors or restarts around the time you posted.

My best guess so far: the map tiles and the building pictures download separately from the game's live connection. If those downloads fail at the moment you arrive somewhere new (New York has the heaviest map tiles in the game), the game never asks for them again. Everything that comes over the live connection, like creatures and health bars, keeps working, which matches your screenshot. Either way the game should retry instead of leaving the map blank, so I'm looking at that.

A few questions so I can confirm it:

1. Did reloading, or panning or zooming the map a little, bring the map and the Oil Wells back?
2. Roughly what time did it happen, and how long did it last?
3. Had you just travelled to a flag in NYC, or had you been standing there a while?
4. Was it blank on your phone and your PC at the same moment, or at different times? Were they all on the same internet connection?
5. Does it still happen now?

Thanks for reporting it.