I would just like to say, I had the same exact issue (though with v1.6.126) and tried all of the same troubleshooting steps. It is now 3 years later (definitely was not a limited rollout issue) and after giving up on it for a while and not using it out of just sheer frustration that I can’t update it, I would like to say that it is STILL stuck on version 1.6.126, says it’s up to date, and from all my searching I haven’t seen any way to get it to a firmware that can actually be updated. Factory resetting just clears settings, doesn’t reset the actual firmware back to the original, which is just wonderful. I am now (three years later, again) trying to use the vacuum again and remembering why I stopped using it… 
I refuse to believe this thing is going to be stuck on the same firmware forever. There has to be a way to manually push firmware to it or something… Though I have not found it.
Thanks Wyze.