Hi Bullets,
I have had that problem too on some notifications in some missions. It's rare though.
But it never affected the outcome of the mission itself as long as I keep doing what needs to be done.
Open the pull down menu on it where the more elaborate waypoint info is about what to do on a certain objective or waypoint, that should still be there. I noticed that only the temporary notification has this message not found error on rare occasions.
If you take that picture in a similar fashion that I did, it should just work out fine.
I made a quick clip of it, to show you how I did it, it's in dutch, but you know what those notifications say anyway I reckon. You can see that it goes through just fine when I then take the pic and turn back to the RWIII.
http://www.youtube.com/watch?v=PPqBnvfIkto
Hope that helps.
Regards,
Fred