I could have sworn that, when working in the ‘Architectural’ (ft/in) units mode with a keyboard, I used to be able to type the number of feet, hit ’ to move onto entering the inches portion of the measurement. That doesn’t seem to work currently.
So, if I’m right and it’s a bug, fixing it would be great. If it’s never been that way, please make it that way. 
Having to combine touch/mouse actions with keyboard when entering foot/inches values gets to be frustrating (albeit very mildly so).
Could you please post your exact app version, your OS version and maybe a short video of this happening with the Tutorial mode options enabled?
I just checked and it seems to be working fine for me on the latest version, exactly as you described.
I first ran into it on the parametric beta, iOS and Windows. 5.460.0.5748
I’m seeing the same behavior on the non-beta though. 5.470.5808 (am I behind a beta version?).
This is non-beta:
This is in the beta on my iPad with the magic trackpad case.