How to enable workflow for opportunity entity?

Hi,

I have activated a workflow for opportunity entity where my first rule is a primary rule and after that i have a few transitional rules. The workflow rules/buttons do not appear on the screen. I also noticed that workflowId field for each opportunity record is null. The name of my workflow is "Opportunity Workflow"

Is there a way to somehow bind or reassign the workflow to the entity?

Additionally, I also checked Workfow &escalation config. where workflow for opportunities is enabled.

Any suggestion are welcome. Thank you.