Making a query to filter on a combination of Tags

Hi All, I was wondering if you could help me out with a specific issue I'm facing.

Scenario:

I've created multiple tags. Example

• Backend-task
• Frontend-task
• Devops-task
• Refinement-needed 

What I would like to achieve

In meeting with the backend, frontend or devops team, I would like to filter down on all tasks that I tagged with Refinement-needed in combination with for example Backend-tasks.

But I can't seem to get this outcome. I only get the outcome where I get both refinement-needed tagged issues + all the backend-tasks issues.

How would you approach this?

This is my current query

tag: {Needs Refinement}, backend-task 

And I would think it should something like this, those do not work:

tag: {Needs Refinement}  && tag: backend-task