Step one: phone hijacks SMS sending to Android Messages, and disables function in Hangouts.
Step two: tablet can only sync my sent messages. Not getting incoming at all.
Step three: re-enable SMS / set default on my phone.
Step four: archive threads because now they’re two on my phone , and the other only gets a copy of mine.
Step five: send a new message from tablet.

Step six: remember that over the past decade, Google has gone from being one of my favorite tech companies to quite possibly the one that pisses me off the absolute most often. I really miss the days when their betas were more reliable than what the rest of us called release quality. Sigh.