When highlighting a defect link in TestRail, it utilizes the integration parameters to fetch JIRA info (via REST) and display an info window about the defect. Like the following:
However, the link highlighted on the dialog is trying to access the REST api url to view the defect, like this https:///jira/browse/. It’s not using the Defect view URL provided in the integration parameters, which causes the access to fail.
Anything else that needs to be configured for this to work.