Can you ping directly from the other FI?
On the FI that is reachable,
#connect local-mgmt
local-mgmt#show mgmt-ip-debug
Your eth0 should be the node IP
local-mgmt#ping IP-OF-YOUR-Problem-NODE
The FI ports don't do trunking, so they effectively need to be access ports.
Assuming you have confirmed that access port vlan is the same on both FI ports?
Are you learning mac address on the upstream switch? You can see the mac from the #show mgmt-ip-debug output.
You can also connect internally from one FI to another with the #connect local-mgmt a|b
Thanks,
Kirk...