Hi Sam,
Sorry to have wasted your time, coincidentally I actually fixed my issue today.
I managed to trace it to the fact that the .ini file provided by you guys was looking for a .bgl under a different name (my .bgl has been renamed after some customisation of the .bgl file).
After editing the file name that was referenced at the beginning of the .ini file, the jetways reappeared!
Maybe this solution will be helpful if anyone else ever faces this issue.
Thanks
Alex