"Unable to check for update" to me could be that there's an intermediate device (or a misconfiguration) that is not allowing the system to reach out to the tenant over the internet (or if on premises, to the target Centrify platform instance).
Simple ping tests can help you pinpoint the issue (name resolution, connectivity).
The connectionTest.exe utility, can be found here:
"C:\Program Files\Centrify\Centrify Connector\connectionTestGui.exe"
This is how it looks when things are OK:
Also note that if the AD object called "proxy" (type: serviceConnectionPoint) that is associated with the Windows system running the connector has been affected, you may need to re-register.
R.P