Hello, I hope the following helps out anyone with the same problem:
I purchased a Melbourne airport (addon) and had exactly the same issue with aircraft parked "inside" buildings and taxing off to one side of the taxiway.
After about two weeks of trying different things the following resolved the issue:
1) Install the new addon (Aircraft/Scenery/Airport)
2) Go to Start/All Programs/VoxAtc
3) Run the VoxAtc Indexer
4) Exit the Indexer and launch Flight Sim