All of a sudden yesterday 3/4/2014 my MarkerWithLabel (Google map API application) is only showing the last marker but the labels all show up. It had been working just fine.
It appears as if the latest google maps update broke something that markerwithlabel code relies on. The same thing happend to some of my maps. We'll have to wait until a fix is available.
The current solution is to set the google maps API version to 3.15 or lower: https://code.google.com/p/google-maps-utility-library-v3/issues/detail?id=296&sort=-id&colspec=ID%20Type%20Status%20Priority%20Fixed%20Owner%20Summary%20Stars