I have this error in FMC
"Smart Licence Authorization Expired" in the message center.
When I try to sync manually i get the below
Failed to send the message to the server. Please verify the DNS Server/HTTP Proxy settings.
Though when I connect to the FMC from CLI I can telnet www.tools.cisco.com.
Does your Smart licensing portal at software.cisco.com show a license is available?
Telnet isn't the best test since the registration and re-authorization takes place over https. Can you curl to the cisco.com page? that will uncover proxy issues (if there are any).
sudo curl -vvk https://tools.cisco.com
It sounds like all of the required connectivity and licenses are in place.
I'd suggest opening a TAC case at this point.