FortiClient - Unable to connect to VPN

We have a number of MacOS clients using the latest FortiClient version (7.2.4.0850)

When a user attempts to connect to the configured VPN, we see the SAML popup in the browser and the client tries to connect, connects and seemingly hangs up immediately.

If I look at the web UI admin interface, I can see the incoming connection

* action: tunnel-up, reason: login successfully

* action: ssl-alert, reason: warning                  <---- (usually, I get several of these)
* action: tunnel-down, reason: User requested termination of service

This generally takes 3-4 seconds to complete

Can anyone guide me in debugging this further?

Thanks in advance