this is what works for me
in global config do this and be sure to change the port to the one you use, i use 9996
ip flow-cache timeout inactive 10
ip flow-cache timeout active 1
ip flow-export source GigabitEthernet0/3/0.1
ip flow-export version 5
ip flow-export destination 33.22.44.11 9996
ip flow-export destination 10.11.13.14 9996
ip flow-top-talkers
top 10
sort-by bytes
cache-timeout 1000
% for each interface to be monitored add this the to the interface sub int command
interface Loopback199
ip flow ingress
ip flow egress
ip virtual-reassembly