Umberto,
There still seems to be a problem with the catering truck, Concorde and Heathrow. When I first tested what you provided it worked fine. However today I had the same issue with the catering ramp not extending to the door.
Because it had worked for me yesterday I started testing to see if their was a pattern and this is what I found at EGLL.
Both Cuisineair and GateAviation failed to extend their ramp to the door even once. Alpha catering worked 100% of the time when they showed to deliver the breakfast sausage. During my testing no other catering vehicles showed up beside GateAviation, Cuisineair, and Alpha.
This is after testing it at least 20x and using reset position frequently.
I wouldn't have expected a texture to make such as difference but perhaps this will be of some use to tracking down the cause of the error.
Cheers
Brent