IPSec tunnel randomly stops passing traffic

Hi All,

 I have a strange problem and I was wondering if anyone else has run into this. We have a Fortigate 200D (version 5.4.10) with multiple IPSec tunnels. We have recently begun migrating from Cisco routers to Meraki. Some of our VPN tunnels on the new Meraki routers will randomly stop passing traffic until we manually reset them, then they start working as normal. The tunnels are configured the same way on both routers. Has anyone seen this behavior?