Second PFsense needs reboot in order to ping switch B

[DrPit]

Hello,

I have a pair of PFSense 2.1 with pfsync enabled and Carp IPs. The first one connects to Switch A and the other one to switch B.

The switches are also stacked (Active-Active)

when the master is alive I can ping switch A and Switch B normally
When I shut down the Master PFSense I can ping Switch A and Switch B through the Back up PFSense.
But when Master PFsense boot again I cannot ping Switch B.
The situation remains until I reboot Back up PFSense.

All other IP of the connected machines have no problem. Just the main switch B ip.