Jira Isues Macro Stopped Working - Status Code 401

[Klay Stack]

A couple of days ago our JIRA Issues Macro stopped working: instead of the link, we get "JIRA Issues Macro: com.atlassian.sal.api.net.ResponseStatusException: Unexpected response received. Status code: 401".  The only thing that we think may have changed on our side is that the former Confluence admin, who is no longer with the company, was removed from the Active Directory around that time. 

When I go to administer Confluence (General Configuration => Application Links), I am told that I don't have any application links right now.  When I try to enter our URL for JIRA and click "Create new link", though, I am told "An Application Link to this URL... has already been configured."

[Klay Stack]

When I edit the page, I can click on "View in JIRA", and the issue displays correctly.

When I click on "Edit", I am told "Login & Approve to retrieve data from...".  When I click on the link, I get HTTP 400 Bad Request.