XG 210 to Fortigate 100C - IPSec Tunnel up, I am unable to pass traffic across tunnel

Question

I am working with my first Sophos devices and am running into a problem passing traffic over an established IPSec VPN tunnel. 
 I have a VPN tunnel established between Site A (Sophos XG210) and Site B (Fortigate 100c). I created a static route for the remote LAN at Site B on the XG Firewall, which is 10.20.0.0/24 on Port 2 and then configured a static route for Site A remote LAN (10.5.0.0/24) on the Fortigate. I have 2 rules in place on either site, at the top of the policy list. Sophos has LAN All->VPN All and VPN All->LAN All, and on the Fortigate Side LAN All->VPN All and VPN All->LAN All. IPsec connection on XG Firewall has Local Subnet of Site A (10.5.0.0/24), and Remote Subnet of Site B (10.20.0.0/24). I cannot figure out why I cannot pass any traffic over the tunnel in either direction. Any help would be greatful!

ZoelDufort · Accepted Answer

With help from Sophos level 2 support, we were able to resolve the issue. Using SHA256 encryption was the culprit, so using SHA1 fixed the problem (supposedly a known issue). As I noted previously that an SNAT rule was required/added, it is not required so was also removed.