[Threshold]

TogglePlayerSpectating(playerid, 1);

When a player is considered 'spectating', AKA toggled to 1, the class selection menu will not show.
People use this to hide their OnPlayerClassSelection so players will go straight through to OnPlayerSpawn.

EDIT: And yes, this is unfortunately in your moving camera function. If you are wanting objects to stream in while the camera is moving, you need to keep it like this, otherwise, just remove it. https://sampwiki.blast.hk/wiki/InterpolateCameraPos