Will MMS to Android users ever work using Mac Messages app with iPhone on Google Fi?

After trying everything else, including rebooting both devices, I signed out of iCloud on the Mac, and it automatically signed in, I rebooted (maybe not necessary?) and it all started working, again.

And then I noticed it wasn't working only for one Android contact, but it worked for others. And then it started working for everyone. I think the key was signing out of iCloud on the iPhone and the Mac, every device, then signing back in, then rebooting, finally standing up, turning three times, then sitting back down.

Please consider all these points in your reply:

1. Messages app on Mac doesn’t exchange MMS messages
2. Messages app on iPhone exchanges MMS just fine.
3. Google Fi on iPhone (all this worked fine using T-Mobile)
4. Apple and Google are blaming each other.
5. Latest operating system updates on iPhone and Mac.

I clicked “Best answer” before the message was sent. Now *nothing* is sent to Android recipients, always reporting “Not delivered" on every message, including plain text messages.