I've been playing with the packet comms demo that is detailed in the docs here:
https://www.gnuradio.org/doc/doxygen/page_packet_comms.html
I've been running the 'packet_loopback_hier.grc' flowgraph from the repo and I'm finding that after a few minutes it stops processing data. No errors. I've traced it to the packet_rx flow graph. It seems to happen at, or after, the header/payload demux.