SmartRF sniffer temperamental as to whether it picks up "high speed" packets

Hello,

 I'm trying to snif BLE packets, with ~6 per connection event at 7.5ms connection interval. Most of the time, as soon as the chip bonds with the master, all packet activity goes dead, but once in a blue moon, when the master and slave bond, the BLE sniffer (cc2450) will be able to listen in on the connection.

How can I make this more reliable? I find it interesting as the CC2540 is only meant to be able to handle 4 packets per connection event. 

Any ideas?

Thanks

Thomas