I have the same problem. My machine is Envy x360 M6-AQ105DX Convertible. It started the day before yeserday.
I had F.21 installed, and Support Assistant notified me to upgrade to F23, 12/23/16. I did so, and it worked.
Then Suppoert Assistant said I needed another BIOS upgrade to F.23 Ap1 1/12/17. I installed it, but it just re-installed F.23. I tried it twice with the same result.
Today, it is still saying I need an updated BIOS (F.23 Ap1), So I went to the HP site and it said the latest BIOS is F,23 Rev 1 dated 1/12/17. I downloaded the SP file SP78934.exe and installed the BIOS yet again. It reinstalled F23, 12/23/16.
Support Assistant is still showing that a newer BIOS is available.
Someone needs to tell HP that they have the wrong SP file associated with the new BIOS.