Xbox One Game Invite

Sorry to hear it. In order for others to receive your invites they would need to be playing on a 360 or on Backwards Compatible games. If you are inviting those on the Xbox One then you would need to send them an Xbox One message inviting them to play

Wrong. Notifications for Achievements, party invites and game invites are discontinued. Nobody can get them anymore. In fact, I believe game invites have been banned from Xbox One, permanently.

It took awhile but I finally got to play with a friend on Dead Rising 3. I'm guessing it probably works the same for most games. You need to invite them to a party and then in the game menu, pause the game and the invite option should be available, at
least it was in DR3 after I reached a certain section.

Incorrect configuration setting is one of the possible reasons why you're unable to sent a game invites to your friend. To resolve this concern, you need to make sure that your NAT Type is Open. To check your NAT Type you may follow the steps below:

1. Click the Start icon and open the Xbox app.
2. Select Settings > Network.
3. Under Network status, check the NAT type.

Once you got the result, please refer to this link and perform the suggested solutions on your computer and your friend's computer.
Follow the steps in order to get more accurate results.

We also recommend that you check your privacy and online safety settings on Xbox.com to ensure that your profiles are allowed to join multiplayer games and parties.

Let us know how things turn out.

Also...can you guys see when your friends come online? I'm not getting any notification if when they come online.