Aws X-Ray does not generate insight

we are using X-Ray to monitor our services. I would like to use X-Ray insight to watch anomalies in our system. I can see there is some insight in the X-Ray generated a couple of days ago. I deliberately changed some APIs and returned errors(500) to have the X-ray generate insight for me but it did not. I am using "Default" group which insight has been enabled. I should mention that when I switch to the insight panel, I see this error: "Could not retrieve trace data." How can I generate some insights?