Whenever you see the red crosses, it's doesn't have anything to do with GSX, because GSX creates its own jetways on its own, doesn't require SODE until they become animated. Even if SODE wasn't installed, you would still see GSX L2 jetways, just they won't move.
The red cross, instead, it's an indication from SODE itself that some objects required by a 3rd party scenery are missing, which might be either a problem with that scenery install, a problem with the SODE installation, or a problem with your simulator, like wrong/missing registry keys.
Try to uninstall SODE and reinstall it, using the latest installer from its site:
https://sode.12bpilot.ch/After reinstalling it, be sure you run the SODE Platform Manager and be sure SODE is activated in all installed simulators, showing no errors.
If the Platform Manager doesn't show any errors, and GSX L2 jetways works, but you still have those red crosses at these sceneries, you can be sure the problem is related to the sceneries themselves.