I saw this same bug in L4 from time to time, but was surprised it is in L5 too; I'm reading along in a reading plan, click the "Mark Read" banner, and my reading plan updates to show that item is complete...but the text where I am reading doesn't...it still shows "Mark Read" for the just-done part. I usually have to close the layout and re-open it in order to clear the problem (this bug doesn't always happen though). A screenshot follows:
