Verify the logs are being written. Run the following commands from CLI:
> show log traffic direction equal backward> show log threat direction equal backward> show log url direction equal backward> show log url system equal backward
If logs are being written to the Palo Alto Networks device then the issue may be display related through the WebGUI.
Run the following command from CLI:
> debug software restart process management-server
note: restarting the management-server will reset your ssh connection.