Honeywell HSIM Error

My Honeywell security panel is integrated via a HSIM module connected to a secondary controller (EA-1), with the entire system run by an EA-5 director.

Last night, the security integration broke. I can see in Composer that C4 is continuing to communicate with the HSIM, but that it lost communication with the security panel.

So far, I have tried rebooting the HSIM via the action button in Composer, power-cycling the secondary EA-1 controller while the director is running, and rebooting the Director. What other troubleshooting steps can I take?

Thanks!