I know since the last patch, in my game at least, Arcade doesn't like to enter McCarran on the first trip or two, and there's a door in Freeside (that leads to another outdoor area) that all companions refuse to go through even when they're literally right behind me (in my face).
But this mostly sounds like you're just outpacing Arcade for some reason. If it takes you a long time to notice he's not following you, you can't be sure if he was stuck but managed to free himself before you noticed...and yet, because you were still moving away while he was briefly stuck, you became outside his 'range' and thus he stands still. Companions have a certain "Follow" range and if, for whatever reasons, they fall behind/outside of that, it can confuse them. Or, alternatively, if they're in the middle of an action and you do something like Fast Travel, it can confuse them upon materializing.
I don't understand though how he gets stuck in the middle of the road, with nothing to get caught on. I merely fast traveled to McCarran, and went straight inside. If he were to get caught on something it had to be some sort of invisible barrier between me and the gate, since it seems impossible to get stuck if there's no physical wall between me and the gate. I think he just went into wait for no apparent reason when I was right there and didn't follow me into the building. I was already halfway across the airfield before I noticed he wasn't following. I waited for 5 minutes and he didn't move an inch on the world map. Just stayed there until I went to him. Usually companions follow me into buildings, and I wasn't that far away before he stopped following me.
I don't think it's the AI range, since as soon as I fast traveled, he apparently went into wait while he was a few feet away from me, unless the range is truly that short in which that it would be impossible to get companions to follow you at all...
I believe when I went into the terminal after he followed me, I was going to get a "like" point from talking to Dr. Hildern, but he just stopped at the door of the Terminal and only came running after I started walking towards him and he then initiated the direct conversation. I don't understand though how he heard everything that happened when he was at the door on the far side of the Terminal, but that doesn't matter.