yep, just had the same experience..
Flashing the update was ok, but the it kept rebooting on twrp
here is the solution i found:
reboot in fastboot mode.
flash shrp instead of twrp (fastboot flash recovery shrp.img)
then reboot in recovery with power and vol+
now you can reboot normally, and the update is applied
Ok, this was the solution for me, thanks man!