GP Relayer and Studio One

Hi everyone,
I have a weird problem. I want to send MIDI from Studio One to Gig Performer via GP Relayer, but GP Relayer only shows up in Studio One as an insert effect. It’s not possible to add it as an instrument on the MIDI track. I checked, and it’s in the correct folder (/Library/Audio/Plug-Ins/VST3), Studio One is also scanning this folder, but only the insert effect shows up (and works), but the instrument is not available. Any ideas?

Do you know this?

Add GP Relayer to an audio track as an insert effect. Then you can select it as an instrument for the instrument track.

Thank you both very much, @pianopaul, @jazzundso, I missed this step with inserting to the audio track. Now it is showing up indeed.