The hotkey ‘s’ will wrongly remove one more charactor in visual mode.
I have encountered this problem since sublime2. but it seems the problem remains unfixed in the lastest version.
Changing default keymap can fix this problem. And here is my sublime-keymap:

{ "keys": "s"], "command": "set_action_motion", "args": {
    "action": "enter_insert_mode",
    "action_args": {"insert_command": "vi_right_delete"},
    "motion": null},
    "context": {"key": "setting.command_mode"}]
}

]