Hi I have same problem with bitlocker key request after update.
After days playing with with different settings i manage to login without that key and without loosing data.
My solution for envy x360 :
stage 1 In bios : boot options, change secure boot to disable . save and exit bios
stage 2 In bios : boot options, change secure boot to enabled , clear all secure boot keys, load hp factory default keys . save and exit .
Start windows and wait bitlocker key request should not show any more.
log in with your credential disable bitlocker or save key on pen drive (not on hdd/sdd ).