How to capture data packets in a fixed data channel

I want to continuously capture packets on a fixed channel 
 ubertooth-util-c2404, ubertooth-btle -p. 
After capturing some packets, it prints: 'LE Promisc - Access Address: d41cb591' and then no more packets are displayed. Has it entered tracking mode? If I don't want to track connections but instead continuously capture packets on this channel, what should I do?
Thanks