Cisco switch interfaces connect to Fortigate HA pair is flapping

[reccenav]

I have a Cisco 9500 Core switch that is connected to my two fortinet 501e's in Hot/Stby mode. I checked my HA Logs and saw that the HA active member kept bouncing between the two firewalls. I had set the HA to monitor the only interface uplinked to my firewalls. When I disable this, the HA quit bouncing. However, the two cisco switches that connect the firewalls (one to each firewall from the same core) are flapping constantly.

Does anyone have experience with connecting Cisco to Fortigates and what I am missing. On the switch, both interfaces are in STP forwarding mode and both interfaces are showing UP/UP on the Cisco. I would have thought that the connection to the Standby Fortigate would be UP/down

Thanks

Derek