It's not possible that you would see any difference between a Trial version of a scenery, and the Full version. Do you recall downloading something else when activating ? Surely not, our files are bit-for-bit identical so, it's not possible the scenery would behave any different.
In addition to that, jetways in KLAS are made using the default FSX system, so they are the only thing not controlled by our software. In fact, they are the only thing left at the end of a Trial session so, it's not possible that any problem with the Trial would have the jetways disappear.
The only thing that can disable a jetway using the default FSX animation system is ANOTHER SCENERY. There are no other ways to disable a jetway.
The most common case of sceneries causing conflicts are .BGL for the same airport supplied with AI Traffic products, which are supposed to enhance the default scenery only, but if you use an add-on airport, they must removed.
You can use the free Simple Airport Scanner utility to search for duplicate AFCADs on an airport, and remove the extra.
