Or, if it's a default airport, it could be possible the marshaller ended up inside a building.
And, if it's not a default airport, but a 3rd party airport with static jetways, this could happen more easily, because on a default airport, when there's a jetway, GSX will reduce the Marshaller distance, assuming that on gate, there will likely be less space behind, but if the airport doesn't have true jetways, GSX can't make out the difference between that and an parking spot in the open, so the Marshaller will instead placed at the best possible distance in relationship with your cockpit height so, if you used a fairly high airplane, like a 747 or a 777 or a 757, that's even more likely the problem.
We are working at an airport customization utility, that will allow to set things like parking radius, marshaller distance, if there's a fake jetway or not, etc. so you'll be able to fix most of the cases.
