Why is it that every time I try to set up a fireteam through the Destiny 2 app on android, players do not join. People join the group on the app really quick and when I send out the invite via the app, one or two people might join in but nobody else does. Is something wrong with my network?
While there could possibly be some connection with NAT type issues, the cause of this is most likely due to the fact that you are not in orbit when you send the invite via the app. In-game, you must return to orbit and then send the fireteam invite. The app does warn you about this and its because it does prevent people from being able to join your game.