The map template fails if there are items in the array of targeted items that have no latlng assigned which can happen if some items do not have address data included yet.
The markers are placed correctly on the map according to the latlng of the items but the info window content is randomly chosen from the array of items. It is not reproducable which info window contains what on the next page load. I reckon that the markers with no geo info are stacked on top of the last marker that had geo info.
Proposed solution: if an item has no geo info then it should not be included in the array of map items io they cannot screw up the info windo content..