Your error logs all indicates something that normally is not possible: the simulator cannot find the objects and it's trying to load an object that we surely install with GSX.
Since it's not possible the objects would be missing after installing, the only possible issue I can think of, is the add-on.xml for the Addon Manager has been possibly corrupted or disabled or couldn't be updated by the installer.
Do you use an external app to manage add-on.xml files ?
Go here:
Documents\Prepar3d v4 Addons\Fsdreamteam Addon Manager\add-on.xml
ZIP this file ( don't post it, ZIP it please, because posting it will alter its content ) and Attach it to a post, so I can check if it's all ok with it.
Also, be sure that file hasn't been mistakenly set to read-only. Another user reported this issue in another thread.