See above:  use the WPS / Power button reset method and then reload your settings (assuming you've reverted to version 47191).

UPDATE!  I finally got through to support.  Reverting to the previous firmware (47191) is PART of the solution.  But there is a catch.  You need to do a hard factory reset using the WPS button (which clears nvram).  I had backed up my config prior to...

Being a little nervous about a beta version (Asus has a history of voiding its warranties with beta firmware), I tried rolling back to the previous official release (47191).  The underlying issue still persists.  I can see at least one core hitting 1...