If you look you can see the icon is changed on the mute and Enable write automation is already turned on. It does the same thing whether the track is armed or not.
 
What is happening is I am playing the project and clicking the tracks mute button. Then I stop playback change the envelope curve to jump. then start playback again and click the mute button turning it on and off. then playback is stopped and the nodes recorded with jump stay placed as they should. While the nodes that were recorded when the curve was not jump all fall to the bottom as soon as playback/automation record is stopped. 

I haven't tested this but come to think of it, a "switch" automation's native action would be to jump...a switch can't have a curve. So it makes sense that a switch would want a jump.

I am getting the same results as Tom but ONLY when there is already an automation line present.
 
This is what I'm seeing in the first part of Tom's video.
 
If you remove the envelope and just use write automation when starting the transport it behaves exactly as it should.
 
The morale is, you don't need to have an existing envelope in order to write automation, in fact the very presence of one prevents a curve from being plotted, even though the nodes are written.
 
Edit:
Further analysis shows that if you change the Automation Write Mode option in the Track Inspector from Touch to Latch causes an envelope to be generated even when there is an envelope.

Very helpful, Jonesey. Thanks for clearing that up.

Good catch Bristol_Jonesey.
 
I guess my urge to watch what was going on while recording the automation was causing the trouble. As soon as the automation lane is opened it creates the envelope.
 
I noticed it also creates the envelope when viewing automation on the main track in TV without the automation lanes opened.  
 
I like the way latch works better than the jump, but I can imagine forgetting it is set for latch when trying to later automate a different parameter like volume.