In this video you can see me using the measurement tool on my PC. When I change the distance between the walls, the numbers vanish and it doesn’t update on the pop up even though the faces are still highlighted. I feel this is a bug and if not it needs to be a feature because the smaller measurement text that appears at the bottom of the work area updates properly.
Also, you will notice that when two faces are selected it defaults to zero. Am I crazy or did it used to show you the distance between the two faces and that changed?
You are not crazy, there is a small inconsistency that you spotted between the panel of the Measurement mode and the general info bar which runs when you are not in the measurement mode. But the bug is in the general info bar as it is not consistent, sometimes it will keep the measurement data and sometimes not. What happens is that depending on what change you make on the body you can get into ambiguous states when the selection changes during modeling in a way that it does not necessary sustains the desired selected measurement. For the use case in the video it happens that the info bar can handle the measurement change, but the info bar in general is great tool for checking on something static quickly.
Our intention with the Measurement mode was to give a robust solution to highlight measurements which are important either to show or to know during modeling. So after pinning we will sustain the measurement until the measured entities exist. It gives you more freedom, you can enter different modeling tools and you can make different selections while the measurement is still highlighted. For your use case in the video I would recommend to pin the given length until you finish the modeling step.