I have Google Maps on a website that sets the marker based on an address.
Here\'s an example (click the location tab): http://www.weddinghouse.com.au/wedding-directo
For me, the problem was the iframe having size 0 (display:hidden) when the map was loaded. I added a delay to load the map after the iframe was loaded. This race condition could explain why some of the addresses rendered correctly.
Perhaps try this:
(thanks to https://groups.google.com/forum/#!topic/google-maps-api/nN0y2pSr2dQ)