I accidentally added a test case to the wrong User Story and also added some test results to it. However, I managed to change the User Story for the test case and it is now showing up correctly.
The problem now is that the test results are still associated with the wrong Work Product and I don't see any way to edit it.
This functionality is working as designed.
Workaround: Please recapture the Test Result for the correct Work product ID.
This is an enhancement that was made in 2023. Please refer to https://techdocs.broadcom.com/us/en/ca-enterprise-software/valueops/rally/rally-help/using/managing-tests/test-case-results/test-case-result-fields.html for more details