Lockheed Martin released a 22.3 MB hotfix that addresses some problems raised by Prepar3D V2.1 users, particularly issues related to addon aircraft (such as night lighting, sunken tires, etc.). It is a list of 49 DLLs plus the Prepared.exe (all located at the Prepar3d main directory). It is advised to backup all these 50 files because they will be overwritten with the new ones.
Owners of Academic or Professional Licenses should get the hotfix from this link.
For those who own the Professional Plus License get this hotfix here.