There is a reason for that.
show config shows the startup-configuration. If you inserted that module while the switch is running and you've not saved the configuration since then, the modules won't be shown.
show run shows the current running-configuration, any additions and subtraction in the configuration will be shown immediately.
If you want the show config to have the same configuration as show run you must execute wr mem or copy run start
HTH,
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Edison.
