Thank you, I got it a couple of days after posting that message. Thank you for the information though, I'll certainly pass it along to anyone else I know who's stuck. Now I only have one left and that's the 'Hogwarts Has Changed' achievement. I'm in the process of my second save and playing through the entire story right up until I get to use the Marauder's Map, which hopefully this time, I won't miss. I wish there was an easier way however. -_-
Are you still needing the LEGO Harry Potter years 5-7 achievement, O Children? I had a similar problem. If you already beat the game don't fret. I got mine as the last achievement.
Try loading your game and do not turn on any cheats. Additionally do not change your characters (i.e. leave Harry and Hermione in the clothes they are in). Then teleport into the tent from the city. If this fails start a new game then reload your previous save and retry the above.