If you load a save before going to Luculla Forest, are the waypoint icons shown on the map?
If so, does entering Luculla Forest make them disappear again?
Try clearing the cache:
- press and hold the Xbox button on the front of the console for 10 seconds until it shuts down
- unplug the power cable and wait 30 seconds
- plug the console back in and turn it on
- log into the same Xbox Live account you were using, start the game and let it sync, if required