VM Fortigate (in GNS3) not passing traffic

We've setup a Vxlan lab with multiple VRFs in GNS3. to allow inter vrf traffic we want to use a Fortigate (router on a stick config). We tried a few different permutations of the interconnectivity between the Cisco Nexus 9k (virtual) switch and the Fortigate. One interface with multiple vlans (on FG side) and trunk on cisco side(with L3 SVIs), also tried L3 ports on Cisco side and separate interfaces for each VRF (corresponding) on the Fortigate side. Sadly the Fortigate isnt passing traffic. We can ping from host1(vrf1) to the Fortigate, including the Fortigate IP for (vrf2) uplink, however it doesn't go beyond that. and Fortigate itself can ping test hosts on both VRFs no issue. the debug on Fortigate is pretty slim, just show's packet coming in, and the firewall finding the route and that's it.

Fortigate has static routes and two basic policies configured(allowing everything between the two interfaces). Fortigate OS is 7.2.7

Any thoughts, ideas?

P.S>:

As a test, we replaced the Fortigate with a virtual cisco router and the traffic passes/reaches both ways with no issues.