Flow graph no exiting after head block termination [possibly packet encoder]

Looking for an explanation,

File Source -> GMSK MOD -> GMSK Demod -> Head Block -> File sinks

Works fine, terminates after x number of bytes have been transferred and
returns.

However:
File Source -> Packet Encoder -> GMSK MOD -> GMSK Demod -> Packet
Decoder
-> File sinks

Does not return after head block limit (just hangs). Seams like the
packet
encode/decode block is not exiting?

Attached flow-graph.