Invite related overlay methods do not work unless game is launched from Steam as an installed Steam game

[zachstronaut]

Methods such as ActivateGameOverlayInviteDialog and ActivateGameOverlayInviteDialogConnectString fail silently (do not produce the correct Overlay GUI) when called from a standalone build launched directly but also not from a standalone build launched from Steam as a "Add a Non-Steam Game..." game.

Other API and Overlay features do work correctly even when the game is a "Add a Non-Steam Game..." game. However, these invite features require that you have actually installed your game for real into your Steam library.

I hope this helps somebody wondering why nothing is happening when they call these methods.