Check and Try the following:
- Delete the DEMO FACILITY in the Merchant Facility Tab, then create a new one with Create Samples. Then set the DEMO FACILITY to both Primary and Active.
- Log out of your instance of Salesforce. Close the Browser, Log back in and try again. If you are running multiple instances/sandbox in the same browser type then this may we make a difference.
- Make sure the user authenticating the App has the Payments2Us Admin Permission Set assigned to them.
- Check the Remote Site settings is correctly setup. You may need to use the Manual Method for setting up the Remote Site Settings.
Salesforce may have moved your instance onto a new pod and this now needs updating. - Check the Payments2Us Error Log