Zones working differently on Android and iPhone?

[+mcaddy]

Having a bit of an issue with a new cartridge I'm developing!

I have drawn some adjacent zones as non overlapping polygons (with a good margin), all works fine on multiple android devices, however on the iPhone I've noticed that on some occasions it shows my player in multiple zones at the same time.

I've not been able to find a way to get the iPhone app to display the zone boundaries, it only shows a pin (I'm assuming this is the polygon centroid) which when I click on it shows a curricular blob, I've some hypotheses as to what might be happening but was hoping someone with a bit more experience using the iPhone app could offer some thing more authoritative.