Not a problem i’ve faced myself but two out of three people I play with have.
Everything works fine up until completing the first race. After that, their controllers disconnect and refuse to re-sync. Changing batteries or controller does nothing.
It doesn’t happen in any other game (Including FM5)
Any ideas?
Have they tried a hard reset of their consoles? Max has an excellent FAQ including troubleshooting guide here http://forums.forza.net/turn10_postst6805_Forza-Motorsport-5---Game-FAQ.aspx although its for FM5 the principles are the same.
Tried this. Still happens 
Are they using the default controller settings ? If not try resetting everything back to the defaults and see if that helps
happened to me at least 3 different times after installing the game. Controller freezes, says my Kinnect needs to be set up. Tried the hard restrt and that cured it, but it happened again…twice…
When you are signed into Xbox Live, go into the Xbox One Settings, go into Devices & accessories. Does the controller show as assigned to your Gamertag? If not, make sure it is.
If the above is correct, still in Settings, go to System to check if an update is available for the controller. If there is no update available, you’re running the current controller firmware from Xbox Live for it. If there is an update available, BEFORE updating, make sure any headset you normally use is connected to the controller and then update, followed by restarting your console.
If that is all current, are you running the controller wirelessly (with a battery), or connected to a USB port? If wirelessly, have you tried wired? You can even use a generic cellphone USB connector from the controller to a USB port on the Xbox One. Or try changing USB ports with the console OFF if you’re wired, and then restarting.
Oh yes, one more thing: If you’re using the Play & Charge Kit for the controller, with the console OFF, remove the battery from the controller, but leave it connected. Restart the console and test to see the behavior. If you still have the same issues, shut down and try a different USB port on the console.
Anyone else having controller issues with the demo? It doesn’t matter where I am or what I’m doing, if I try to go back to the Xbox home menu, the controller stops responding. If I set the controller down and it turns off, I can turn it back on, but it won’t respond. Only thing that fixes it is a hard reboot of the console. If this is how the full game plays, I’ll have wasted $100. Any help would be greatly appreciated, thank you.
Yeah I’ve seen a similar issue after the controller goes to sleep.
I’ve sent this in as a bug. In the meantime, use Kinect to start another game, then go back into FH2.
I’ve put about 10 hours into the demo and not a single problem so far with the controller.
Hey I’m having a problem with my controller disconnecting while playing the demo. Usually happens if I try to go back to the Xbox home menu or if I let the controller sit until it turns off. It’ll turn on again but none of the buttons do anything. Only thing that has fixed it is a hard reboot of the console. This is getting really annoying seeing as I have to restart the game over and over. I know some of you people are also having controller issues so any help on the subject would be appreciated. Thanks.
How’s that work exactly? I’ve never used the Kinect, never even plugged it in lol
(EDIT)
I just got off the phone with Xbox Support and we have figured out a work around for the time being. What needs to happen is to turn off Kinect Sign-in, and then you will be good. I have tested it and it works, also, keep in mind to turn it back on with every patch to test if it has been fixed by that point! Hope that helps!!!
I primarily use the play and charge cable, unfortunately they have it too heavy near where it connects to the controller, so it “unplugs/disconnects” very easily. Well, in this game and in the demo, if that happens, then you lose the controller period, the only option is to power cycle the console. Sometimes that is not enough, so you have to hard reset it. It’s not very fun that I have to be so careful with my controller so that I can continue playing, ALL other games do not have this issue, this is the first and only one for me so far.
(Edit)
It also makes the Kinect stop working if you don’t hard reset it. Unfortunately Microsoft have not made it an option that matters on resuming games quickly, I have it unchecked, but it always goes right back to them. That is why you have to hard reset the console, by holding the power button down till it goes off. 
This has happened to me as well. What’s weird was the same thing happened to me in the demo of the game. It hasn’t happened with any other game ever. It’s not the worst problem in the world as you just have to keep playing or your controller active.
But it is a weird annoyance. If anyone else could confirm it that would be cool. Then again who will stop playing long enough to test it lol?
Oh by the way my controller is a wireless one with batteries. No play and charge kit so I don’t think that’s the issue.
I use a USB cable to connect the controller as well. The controller would disconnect during the demo constantly. I had to go wireless just to play the demo. Now I have the full version of the game and am playing using the wired USB cable. I got my first disconnect as the second race was loading. No way to reconnect the controller. Had to do a hard reboot. Once I rebooted the controller re-connected.
UPDATE: The controller crapped out again as the third race was loading. I lost sound and the car began revving by itself. I had to do a hard reboot. I am going back to wireless to see if that works better than wired.
I had this issue also. It is definitely a Horizon issue. They need to fix it ASAP. Very very annoying. You have to hard reset it every time it happens.
Are you wired or wireless when the controller disconnects?
Wireless. Also disconnects with play and charge kit.
Why is it that when my controller turns off due to inactivity that it completly unpairs from my Xbox one? It does the same thing on fm5 and its really very annoying. You have to do a complete hard reset of the system to get it to pair again, going thru the pair a controller steps had no affect. H2 and fm5 are the only games iv played that do this so clearly it’s something wrong with the root programming of the games. I seriously doubt yall will fix it but it sure would be nice. We pay $60+ for these games and they always have stupid little bugs like this, it’s ridiculous!!
anyone else have their game freeze after their controller randomly disconnects? a hard reset is the only solution that has worked for me so far…
I have never had disconnect issues. I do have Kinect enabled, and I am running the latest preview dashboard as part of the preview program.