This will happen only on a machine installed more than one Inspect instance. (In your case, test and production instances)
Inspect uses a local machine as a small host server, so, the user (Windows account) should have a privilege to open a service port to allow to run the server with a specified port number.
The test Inspect instance tries to use another port number. However, it's not configured your account uses the port number.
Here is an article about Inspect service port number settings.
Inspect Service Port Settings
To run Inspect Service, Windows administrator should run the following script to reserve the specified URL for non-administrator users and accounts.
Script:
netsh http add urlacl url=http://+:<port>/ user={domain}\{account}
ex) netsh http add urlacl url=http://+:80/ user=kal\zoodata Available port numbers: 80, 591, 8008, 8080
By default, Inspect Desktop uses port number 80
Reference: