Power BI Developer Visual not present; pbiviz start is listening

I have followed instructions for Power BI's Developer Visual Setup and am able to successfully run pbiviz start against NPM's powerbi-visuals-tools running Node.js 6.10.0 (x64):

info   Building visual...
done   build complete

info   Starting server...
info   Server listening on port 8080.

My Power BI is configured to allow developer visual for testing. However, Power BI doesn't show the developer visual button. It seems this is due to PBI not being able to connect to the server on port 8080, so I checked netstat -an to see if the port is truly open, which it is:

>netstat -an | findstr 8080
  TCP    0.0.0.0:8080           0.0.0.0:0              LISTENING
  TCP    [::]:8080              [::]:0                 LISTENING

I then tried to connect to the port (127.0.0.1:8080) from PuTTY as telnet, and it immediately fails with "Connection closed by remote host". If it's any indication, when I kill pbiviz, the open 8080 port lines disappear.

Is there something else that needs to be done to make this port available?

I discovered that I can run pbiviz package, generate a .pbiviz file, and load it from PBI by clicking ... -> Import a custom visual, and the test visual that I created works. So PBI is playing nicely with the sample project created by pbiviz new MyVisualName. It seems this may be a Node.js server issue, not so much Power BI?

via user655321