IPSec Tunnel UP with no traffic -> ESP packets blocked

[mosquito]

hi all,

i have a very strange behaviour with an ipsec setup between a meraki box and an opnsense fw. phase 1 and 2 are both up and after a reboot (of opnsense) everything works fine. but after some time i'm not able to get traffic going over vpn. i can still get the tunnels up and both ends show the p1 and p2 up, but no traffic can pass. when i check the live packets i see ESP packets from the meraki device, but they are blocked by opnsense (see screenshot)

rules are automatically created by vpn and they are in place and match the traffic that is blocked (but should be allowed according to the rules)

to solve this i simply need to reboot opnsense and all is good again, but that's not really a solution i like .

to me it looks like a bug and i think i did not happen before i installed the most recent update, but i can't tell for sure. can someone advise?