A friend of mine got two Dots (one for the living room and one for his bedroom).
He linked his Harmony hub with the living room Dot and created some basic commands.
A lot of times, he would issue a command, the Dot would respond instantly, but nothing would happen. About 4 minutes later, the command would happen and the TV would respond.
We don't think it has to do with the hub, since the app would work flawlessly. I'm wondering if it might have something to do with any limitations with the wifi router (which is literally 4 feet away).