I have a weird issue with assigning parking for vehicles in stands. I assigned a large pushback truck to a stand, however when the truck gets there it just waits on the road for a couple of seconds, then the assignments gets deleted and it goes to park elsewhere.
I have had this issue before too sometimes, and it’s usually because the stand is closed, check to make sure the stand isn’t closed. If it wasn’t closed, try closing and opening again then assigning the vehicle back to that stand.
This function generally does not work for me, and my solution is to just put a parking lot or garage near the main operations. the vehicles will sort themselves out and it should just be a little longer wait.