FortiGate GUI keeps logging out on VM trial setup

Hello,

We are testing a FortiGate-VM trial setup, but the GUI still logs out immediately after login.

We have already verified the following:

• GUI certificate is set correctly.

• Admin idle timeout has been increased.

• https is enabled on the management interface.

• NTP time sync is correct.

• httpsd process is running normally.

We also tested:

• different browser,

• incognito mode,

• cleared cache and cookies,

• login from the correct trusted host / source IP.

Even after all of the above, the GUI still kicks us out after login, while SSH access remains stable.

Has anyone seen this behavior on FortiGate-VM trial or evaluation mode? Is there any other VM-specific GUI setting or known issue we should check?

Thank you.