Check Redirect links give a 401 error

Hi, just installed your plugin and imported from Simple 301 Redirects and the old URL list. All looks great.

But in the admin list of redirects, if I use the Check Redirects link I’m getting a 401 error in a popup:

“Check redirect for: https://www.matki.co.uk/installers/
Expected: 301 to https://www.matki.co.uk/services/

Found: 401

Agent: Not using Redirection”

If I just use curl, I get a 301 redirect, showing x-redirect-by: redirection. If I just use my browser (Safari) I also get redirected correctly.

Just want to make sure that this is nothing to worry about.