Well, that really is strange! I am using the same version of the app as you, but my text formatting bar looks totally different. And of course, I have no button to toggle it on or off. I am using Android 7.0, so perhaps you only get the button in the even-numbered versions of Android, not the odd-numbered versions? ha ha.
And Dave, I just saw your post in the other thread where a user recently updated their app who has NO text formatting bar and no button to turn it on! Weird indeed.