As ringo da whoop said.
Another thing you can check(that would have the same effect as ringos solution if you did infact save them into the default group) is that if you have a custom group for meshes, and it's a rather big list, new saved objects from the object maker wont show up in the map maker, just because of the size of the list.
Try to create a new group for those objects you try to get in the map maker, and save them to that instead. Might help