Okay, so perhaps the same thing happened to me. After great frustration, updating the app, and uninstalling/reinstalling, in tapping around all of the various options in the Android app, I tapped on the a icon at the top of the page (between the redo icon in the attachments icon). Lo and behold, the formatting toolbar is back! A bit embarrassing, but I thought I'd share it in case this is the issue you're facing too. 🙄