I suggest restoring the original file, which should be done by removing it, and reinstalling the Content.
In theory, the GSX Control Panel should be able to find the original jetway and patch it, even if the file is not exactly the same as the original one. However, if objects have been reordered by MCX, it's possible they cannot be found because they are in a very different location of the file, and the Control Panel doesn't search the entire file, only the general area in they were supposed to be found, as an optimization.
If you could send me your modified file by email, I could check this.