Your problem is caused by a timing error, the creation of the model cache is taking too long, we don't understand what's causing this, because P3D4 should have the smallest model cache of all, since it has far less model variations due to having Render to Texture available.
The problem seems to happen randomly, the only solution I found for the time being, is selecting "Restart Rebuild the airport cache" again, until it works.
Go to a default airport where GSX has replaced the default jetways and choose "Restart Rebuild the airport cache", and pay attention when the jetways come up. They might take even 20-30 seconds or even more, if they don't show up, it's likely you got that error again, so you need to try that option again, until it works.