Thank you for your help! After finally getting around to trying your advice though, I suddenly had an updated version of the SmartThings Android app (complete with updated visuals) and everything just started working (with the SmartThings Edge drivers beta) with my next inclusion attempt.
For posterity, I:
Locked the lock (this somehow seems important)
Started with “scan QR code” in ST
Entered [programming code], gear, 7, gear, 1, gear (each time you hit Gear, the keypad lights show you that you’re still on the right track)
in this case it indicated success in about another 4 seconds
Same process as before, but the updated app seemed to do the trick. Neither the Yale documentation nor the Yale support agent I called laid out the steps quite like above.
I did also try the philh30 driver and it works but there doesn’t seem to be any noticeable difference.