test_feedback_update occasionally fails due to an invalid access token

The test test_updating_own_feedback_doesnt_invalidate_other_tutors_assignment from functional_tests/test_feedback_update.py may fail because the first tutor is unable to enter the Feedback-History page (or select a Feedback Instance) as they are met with an "Invalid Access Token" Error Message. This does not happen when the test-steps are repeated manually, and occasionally the test goes through without any problems, so this is a rather peculiar Error.

The testsuite says the Test fails due to a Timeout Exception on the wait for either the feedback-row elements, or the submit-button on an accessed feedback instance, but both cases are due to the "Invalid Access Token" Error, as can be seen from the Screenshot that was exported from when the test failed: