If you're trying to control a plugin parameter directly from your physical hardware, you may be tempted to use the plugin's MIDI mechanism, possibly because that's all that was available to you before you started using Gig Performer.
However if you're using Gig Performer, you will generally want to avoid direct MIDI control of plugin parameters and you should always use the plugin's host automation support and associate plugin parameters with Gig Performer widgets.
If your goal is to control a plugin parameter from a slider or knob on a physical controller, you will do this by associating a Gig Performer widget with the desired plugin parameter and associating your physical slider or knob with the Gig Performer widget.
There are many benefits to this more modern approach to controlling parameters, click here to learn more: https://gigperformer.com/use-host-automation-rather-than-midi-to-control-plugin-parameters/