What is wrong with this GNURadio flow graph? I am simply trying to modulate a wav file sampled at 22.05kHz, then demodulate it.  The audio output is choppy and I get errors in the console output (&quot;volk warning, no arch found... though I've run the profiler.  And aUaUaU....).  I guess the issue is with matching sample rates but I've gone through the graph several times and haven't found it.
Also maybe this is related: after I add the bottom row of components (channel model and beyond) the constellation diagram for the transmit side changes to flat.  Meaning, instead of a circle, it's a line (second screenshot below).  What's going on?
I wasn't alone it seems.  It is apparently a known issue and the solution here solved this for me as well: https://github.com/gnuradio/gnuradio/issues/1516