c6509 - Flows in one direction only

Hello,
Can any one advise on where i might be going wrong with the issue below?
I have customers on a 6509 on a 48 port ethernet card - WS-X6248-RJ-45
Traffic goes from customer to internet and back again through an svi on a CEF720 4 port 10-Gigabit Ethernet card.
I have flows for outbound traffic - customer to internet - but no inbound traffic, internet to customer - i see no flows in the flow cache or on the software despite obvious inbound and outbound traffic patterns observed on cacti - customers have no other internet connection - it's all in and out through this device.

Here are my interface configs:
interface FastEthernet7/7
description CUSTOMER
ip address x.x.x.x x.x.x.x
ip flow ingress

Here is the wan connection:
interface TenGigabitEthernet1/1
description To BORDER ROUTER
switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 561
switchport mode trunk

Int Vlan 561
description SVI to BORDER ROUTER
ip address x.x.x.x x.x.x.x
ip flow ingress

Finally my nde config:

ip flow-cache timeout active 1
mls netflow interface
mls flow ip interface-full
no mls flow ipv6
ip flow-export source GigabitEthernet8/48
ip flow-export version 9 origin-as
ip flow-export destination 10.16.143.222 9996
mls aging long 64
mls aging normal 32
mls nde sender

Any advice would be much appreciated. I suppose that configuring ip flow egress on the fast ethernet interfaces is an option but i beleive there may be a performance hit with running this.
Thankyou
Richard