Hi,
I would suggest you to check if the Site to site is UP. If the tunnel is UP, then initiate ping and perform a packet capture on both ends and see if the ping is even reaching the other end. If it does and response is not reaching Azure, then check the Rras routing.
If it's other way around that ping is dropping at Azure side, then check the effective routes of your VM and see if you can find the on-Prem routes to VPN gateway.
Regards,
Karthik Srinivas