[Discuss-gnuradio] Differential Encoder Dropping Tags

I think I've discovered a (new?) bug with the Differential Encoder. I have the output of a Packet Header Generator block feeding a Differential Encoder which feeds into a Tag Stream Mux. My flowgraph has been freezing on the following:

FATAL: Missing a required length tag on port 2 at item #25216
thread[thread-per-block[21]: <block tagged_stream_mux (75)>]: Missing length tag.

To fix this, I place a Tag Gate in front of the Differential Encoder and a Stream to Tagged Stream block after it. This has the effect of manually adding the tag that should pass through the Differential Encoder but isn't. This fixes the freezing.

I've been using this setup for a good while now, more then six months. Only recently, within the last month, have I had this problem. Maybe that will help narrow down the bug.

Rich