Reboot the LUH machine, if the issue persists then check the following:
1. Go to Start -> Run -> Services.msc
2. Verify the LUH service is running (ssCSPProxySvc)
3. Start the service if it's not running, you may need to try and start it multiple times.
4. Start the SEP.cloud client service, this may take a couple tries
5. Verify that the issue is now resolved.