Hang on, I have a fix for you.. I'll try posting it on here or if you have the ADE Airport Design Editor you can do it yourself, you need to fix not allowing your AI to park there by telling the editor that those UALX GATES only taking out the UAL or making the size of the gates where only the express will go there..
I'll still try to send that file but incase it don't work, that's what you need to do on your end.. I'll have to try sending my afcad I have made up for it tomorrow. Its not on this PC..