I just launched our forum, but the advanced search bar does not seem to be displaying.
What do you mean by advanced search bar? Can you share a screenshot of a site showing the bar you are wanting? It could be you need to add or enable a theme component.
I did, I think the theme isn’t accepting the components
Hiya Sidi 
nice to see you again 
The advanced search banner is definitely working, I just installed the latest version.
If you go to your /admin/config/customize/components page you should see it like this, showing it enabled and what theme it is on. You can click the ellipses (3 dots) to check for updates. To change the component settings or add it to a theme, click the Edit button.
Since your screenshot shows you as logged in, you may want to check the Show for component setting to make sure you have it showing for the users you want to see it:
Also, I notice your logged in user is an admin - I suggest you use a non-admin test user account to view changes you make to your forum. In fact, having one test user account per trust level is ideal (for hopefully obvious reasons).
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