Contacts are not visible in opportunities, dont show up in subpanels

If anyone can help me, I will be forever grateful. I checked the relationships and it is marked correctly as many to many.

The other relationships look fine but this one is not working.

When I am in a contact and I want to associate it with an opportunity, I cannot see that contact when I am in the opportunity.

Other than this, I love SuiteCRM.

Thank you,