Systems Management

We are trying to get our KACE SMA (12.1) to integrate with our KACE MDM tenant. 

I've been following the instructions to setup a discovery schedule on our SMA, but it doesn't seem to want to pull our mobile devices in from MDM. When I run the schedules task, the following is the error that it being logged in the Discovery Log:
KBScanTask->scanExternalSources() - Error occurred while discovering KACE MDM devices: Request failed. The service may be unavailable or down for maintenance:

I've checked our firewall, and have not found any incidents where the traffic was blocked. 

Not sure what I've missed in the setup of the MDM or the SMA. So any insights will be welcome.