Thank you for posting! When using the lookup feature in TestRail or using the ‘Push’ dialog, TestRail submits an API request to Jira in order to retrieve the item’s details and display this on screen. If you are receiving a 401 error when performing either of these actions, this would indicate the credentials saved in TestRail for your account are not correct, causing the API request to fail.
Please double-check the credentials entered in your account under ‘My Settings > Settings’ to ensure you have entered your Jira email address along with an API token for your account. We have also released a video walkthrough for updating these settings:
I hope this helps!