It's been over 3 weeks since it's release, and I still don't have it. Apparently, it squashes a lot of bugs I have with 1.11, so I'm eager to get it. If you've somehow tricked Google into giving it to you, I'm all ears as to how.
1.12 was made publicly available on March 7... knowing Google Play it might take a few days until it's available to everyone (I believe Plex is using staged/phased rollouts).
You can / need to join the Plex for Android Beta program (https://play.google.com/apps/testing/com.plexapp.mediaserver.smb) to get the releases while in beta/preview stage (in that case you could have gotten your hands on 1.12 on Feb 28).
Thank you sir. Everything I needed to know.