M6220: Bug on the new firmware 3.1.5.2 (mutlicast)

Hi,

First, during the upgrade from 3.1.3.9, i encountered the following bug: the lag was in a unstable state.
I was forced to remove the vlan and the trunk, then to recreate the trunk and tagged the vlan.

Most important, i encounter a very annoying bug.
It seems that sometimes some multicast packet are dropped:
we use vrrp protocol for high-availability, in a high load network, our passive server don't receive some vrrp (multicast) packets,
(i can see that with tshark).
The same situation occurs with or without the lag, with or without the storm-control, with or without the igmp snooping.

Can you advise me, on how to solve this problem?

Regards.

P.S:

the snmp bug is corrected, the one to backup the running config with snmp.
But now, i can't no more fix the filename:

/usr/bin/snmpset -v 2c -c xxxxx -m FASTPATH-SWITCHING-MIB xx.xx.xx.xx agentTransferUploadMode.0 i 1 agentTransferUploadServerAddressType.0 i 1 agentTransferUploadServerAddress.0 s $tftp_server agentTransferUploadDataType.0 i 3 agentTransferUploadFilename.0 s running-config agentTransferUploadStart.0 i 1

Before, i was able to do that:

agentTransferUploadFilename.0 s $host_date

but not anymore.