The test plan only shows result from test runs created from the test plan. Other results, i.e. results from other test runs not created or linked to the test plan, are not taken into consideration.
My guess is that the results you pointed out stem from test runs not created or linked by the test plan.
You can also link a test run to a test plan after test test got created, but it needs a 1-liner of code, see here:
Best regards,
Alex