[Discuss-gnuradio] Flowgraph locking up with Stream Mux

I’m somehow getting a simple flowgraph to lock up GNU Radio. It locks up every time I run it, after roughly the same amount of time. As you can see in the attached image and GRC file, I’m feeding two inputs of a Stream Mux block from the same upstream block. Do you imagine why that might cause problems?

 

I know there are other ways to do what I’ve shown here, but locking up seems like a bug.

 

Thanks,

Sean