It seems that chat must be minimized after it is fully initialized. Lets call the function a bit later - when player is activated.
Add this code to the very end of the SetMySettings.lua:
Lua Code:
EVENT_MANAGER:RegisterForEvent("SetMySettings", EVENT_PLAYER_ACTIVATED,
function(event)
EVENT_MANAGER:UnregisterForEvent("SetMySettings", event)
CHAT_SYSTEM:Minimize()
end)
(tested and working)