New to the If then world. Not sure why this does not work.
To answer that, we'll need to know what isn't working.
But what can help you figure out some of this on your own is to enable logging. I'd recommend at least action and event logging. That will show you what (and if) the rule is executing and when. As-is, given the current states of your devices, whenever the "Test Switch" turns on, it looks like Master Light should flash, the notification should be spoken, then the lights should turn on and the volume adjusted after the delay. There are lots of things that could go wrong there (switch event not firing? light doesn't support flash?), so more information would be helpful--but this might get you started on your own, too, if you want.
I'd also suggest you break the one big rule into smaller rules. It will help you compartmentalize and figure out which parts you need to debug, vs which parts are working fine. When you're done debugging you can either figure out how to combine the rules or just say "hey it works, f* it."
The second else if should fire- Flash the light, speak over sonos. Then turn the light on.
Nothing happens. It is like the rule is not installed. I get nothing in the events or logs.
Flashing the light was killing the rule. Seems to be work now that I took that out.
Does your light have a "Flash" command on the device page? If not, this rule action won't work (and you'd probably get an error in the logs, explaining failure of subsequent actions).
That switch did not have the flash feature. So it was indeed killing the actions.