Custom audiance not showing existing meta pixel

Hi,

I have created a pixel by following these link
https://www.facebook.com/business/help/952192354843755?id=1205376682832142
I used partner integration -> used this plugin and I can see the pixel in my website and the data is collected from it.

My issue is I am trying to create a custom audience for creating a Lookalike audience. When I click Create custom audience it not showing the pixel I created above. It shows a new pixel name and asks for pixel configuration.

Please guide me how to resolve this.

The page I need help with: [log in to see the link]