Help :-( Access google from internal network ok but unable to ping

At Policy&Objects > IPv4 > Policy check your internal>wan1 policy

What services are listed?

If you unsure simply provide a screenshot of the policy list going from your internal interface to your wan interface

Yes, Service in the Firewall policy should be creating an issue.

If the policy is allowing service 'ALL' or includes ICMP as well, then verify if there is any policy route created