Recently we discovered a new bug. Several people reported it on our forum. If a Place is added to a map outside the area you want the map to include and then you delete that place, the site fails to recompute the map bounds. That means that the map stays zoomed out too far, spoiling the display of your markers.
We are working on a fix, but if you have a map which is looking a little wonky because of this bug, I can fix it for you right away.
You can leave a note on the forum if you want me to fix your map, or email me tracy-at-platial(dot)com. Be sure to tell me the url of your map.