I have no blade-related experience, but did you put the vswitch ports that connect to your pfsense
vm's, and which are to take part in CARP, into a port group that has promiscous mode enabled?
I usually create a duplicate port group (same vlan, same vswitch), which has promiscous mode
enabled, and put the pfsense interfaces into that port group, and all vm's that use the pfsense as
a gateway into the port group with promiscous disabled.