I was so hoping that your “model order” aside would have been the solution.  You’d have been a champ to post the video even though you found out what was going on… 

When you look in the console do you see whether any of the models have gotten True ID’s (an indication that the new model has actually saved).  
Might it be required fields? 

Yes. The Account model saves. I can then press the button again and the Opp model saves.

So? Is this a bug then? The only way around this was to create two separate save actions.